18 years old, stiff neck, lump in right side of neck, headache, jaw pain going on for 3 weeks, gets worst when smoking?

Symptoms: Symptoms indicate infection. Source of infection has to be discovered and treated. You say smoking makes it worse. Concern is the harm smoking can do, and it may kill you. Please see Dentist or Physician to begin the diagnostic process with health history/medication/smoking review, examination, possible imaging, possible lab tests, etc. Once diagnosis established treatment can be prescribed.