Inclusion Criteria:

          -  Participants must have histologically or cytologically confirmed squamous cell
             carcinoma of oral cavity, oropharynx, paranasal sinuses, nasal cavity, hypopharynx, or
             larynx. Squamous cell carcinoma of unknown primary in cervical lymph node can be
             included only if p16 status is positive.

          -  Must have recurrent or metastatic HNSCC stage III/IV that is not amenable to local
             therapy with curative intent (surgery or radiation therapy with or without
             chemotherapy).Patients with persistent disease following radiation therapy
             administered with a chemotherapy sensitizer may also be included.

          -  Must have progressed on at least one prior line of chemotherapy, targeted therapy,
             palliative radiation, and/or biological therapy regimen for their recurrent and/or
             metastatic HNSCC. However, if patients are likely to be intolerant to standard
             first-line systemic chemotherapy, the patients are eligible to enroll to this study as
             the first-line therapy. Additionally, patients with persistent disease or
             platinum-refractory recurrent disease may enroll in this study as a first-line
             therapy.

          -  Must NOT have any systemic therapy for recurrent and/or metastatic disease except if
             given as a part of a multimodality treatment (i.e. re-irradiation and systemic therapy
             for curable intent of locally recurrent disease).

          -  Must have measurable disease, defined as at least one lesion that can be accurately
             measured in at least one dimension (longest diameter to be recorded) as outlined in
             RECIST version 1.1.

          -  Must be ≥ 18 years of age.

          -  Life expectancy of greater than 3 months.

          -  Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2.

          -  Must have normal organ function: Absolute neutrophil count > 1,500/μL; Hemoglobin > 9
             g/dL; Platelets > 100,000/μL; Total bilirubin ≤ 1.5 mg/dL X institutional upper limits
             of normal (ULN); AST (SGOT)/ALT (SGPT) < 3 X institutional ULN (or 5.0 X the ULN in
             the setting of liver metastasis); Serum creatinine of ≤ 1.5 X ULN or creatinine
             clearance > 40 mL/minute (using Cockcroft/Gault formula): Female creatinine clearance
             = (140 - age in years) x weight in kg x 0.8572 x serum creatinine in mg/ dL; Male
             creatinine clearance = (140 - age in years) x weight in kg x 1.0072 x serum creatinine
             in mg/dL.

          -  Participants, if sexually active, must be postmenopausal, surgically sterile, or using
             effective contraception (hormonal or barrier methods). Female participants of
             childbearing potential must have a negative serum pregnancy test within 7 days prior
             to enrollment.

          -  Ability to understand and the willingness to sign a written informed consent document.

        Exclusion Criteria:

          -  Have experienced grade 3 or above skin toxicity from prior Epidermal growth factor
             receptor (EGFR) inhibiting therapy.

          -  Have experienced grade 3 or above toxicity from prior anti-PD1 therapy.

          -  Have p16 negative squamous cell carcinoma of unknown primary in cervical lymph node.

          -  Patients with primary nasopharynx or salivary gland cancers.

          -  Patients who have had chemotherapy, biological therapy or definitive radiation within
             4 weeks of the study enrollment or those who have not recovered from adverse events to
             ≤ Grade 1 due to agents administered more than 4 weeks earlier.

          -  Had undergone any major surgery within 4 weeks of study enrollment.

          -  Had undergone any palliative radiation within 2 weeks of study enrollment.

          -  Have had other investigational agents within 4 weeks or 5 half-lives, whichever is
             shorter, of the study enrollment.

          -  Have known leptomeningeal metastases or untreated or symptomatic brain metastases.
             Treated, asymptomatic brain metastasis can be included.

          -  Uncontrolled intercurrent illness including, but not limited to, ongoing or active
             infection, autoimmune disease requiring systemic steroids, symptomatic congestive
             heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric
             illness/social situations that would limit compliance with study requirements.

          -  Have a condition requiring systemic treatment with either corticosteroids (> 10 mg
             daily prednisone equivalents) or other immunosuppressive medications within 14 days of
             study drug administration. Inhaled or topical steroids and adrenal replacement doses >
             10 mg daily prednisone equivalents are permitted in the absence of active autoimmune
             disease.

          -  Have clinically relevant coronary artery disease or history of myocardial infarction
             in the last 12 months or high risk of uncontrolled arrhythmia or uncontrolled cardiac
             insufficiency.

          -  Have uncontrolled or poorly controlled hypertension (>180 mmHg systolic or > 130 mmHg
             diastolic) at the time of enrollment.

          -  Prior treatment with a combination of cetuximab and a PD-1/PD-L1 inhibitor. Prior
             treatment with cetuximab or a PD-1/PD-L1 inhibitor is allowed as long as not
             previously given in combination.

          -  A history of allergic reactions attributed to compounds of chemical or biologic
             composition similar to those of cetuximab and/or nivolumab.

          -  Pregnant or breast-feeding.

          -  Known active HIV, Hep B, or Hep C infection. If not clinically indicated, the patients
             do not need to be tested.