My head has been aching for weeks and ive got pain on my right shoulder going down to my chest. what can be the problem?

Weeks = see doctor: Most people get a headache at some time, such as from colds, infections, lack of sleep, too much driving, long hours on the computer, stress at work, etc. Over-the-counter options include Tylenol, Motrin, Advil, Aleve, Excedrin, and are for Temporary Use. A bad or increasing headache, recurrent headache, weird headache or one that won't go away (as in this case) should be examined by a doctor.

Pinched nerve : You can have a pinched nerve and this could be a radiating pain to shoulder and chest. Anti inflammatory (Motrin/Aleve) will help. May need MRI or Nerve studies especially if there is numbness or tingling associated. Neck exercises are also helpful.