I had a sharp pain around the cervical spine for 4 weeks now. It hurt the most after sleep (or lying down) and strenuous exercise (muay thai).?

See you doctor. I can't diagnose your problem without first seeing you and doing a full workup. However, what your experiencing is not normal. One possibility for your complaint is cervical facet arthritis-a fairly common condition. Another possible cause is a small tear in the disc. In any case, see you doctor and get feeling better.
See below... I would see your doctor for them to evaluate your symptoms. Since they are still present at 4 weeks, i would obtain x-rays to make sure there is no fracture. Depending on your symptoms and physical exam, they may want to obtain an MRI as well.