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Pain in just right side of head can be due to compressed cervical spinal nerves, pulled muscles, torticollis or wry neck (spasm of the sternocleidomastoid muscle) or even due to internal ear infection. It can also be due to TMJ or dental infection. I think you should discuss these possibilities with your doctor. It is difficult to comment beyond this without examining.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
I would definitely go to a doctor and have it checked out. My mother died from a brain aneurysm which bled. She was having severe headaches for a few months at least before it bled. If they do a cat scan with contrast they can see if anything is there and if it is starting or likely to bleed. Don't take any aspirin as this will cause bleeding.