I have a lump inside my head on the right side..... what is it?

You have a tight muscle you are feeling there and it is the cause of your headache. To get rid of the lump and the headache you have to free up your neck muscles. Your neck muscles go to the top of your head where they connect to muscles going around your head. When the neck muscles get tight they pull on the head muscles and when they go into pain you have your headache. Here's how to free up your neck muscles to get rid of those pains:

Neck

Put your hands alongside your head so your thumbs are on the front of the muscle under your ear and your fingers are on the back of the muscle behind your neck. Squeeze your thumb and fingers together and hold. Relax your body. When your fingers and thumb touch, about one minute, slowly lower your head as far as you can, release the pressure but hold your neck lowered for another 30 seconds.

For best results relax your body first by taking a deep breath and exhaling then remain this relaxed.

I don't think it's a tumor. But I definately think you must go get it checked out by a doctor. When my sister was a baby, there was a flap of skin that got caught between the left and right side of her skull as her fontanell (the soft part in a baby's head) was growing together. As she got older the skin began to grow. It didn't hurt her, but a large lump appeared in the middle of the top of her head. She had to get it removed as there was a worry that it would begin to cut off blood supply. Two questions you must ask yourself...How long have I had this bump for? Has it been hurting ever since you noticed the bump? If the pain is throbbing don't just have a pain killer, see a specialist...i.e. a neuro surgeon or someone like that. Your head is a very fragile place and you must look after it. you only have one! See a specialist.

And it hurts you say. Why haven't you made a doctors appointment yet. It's probably more of a cyst than a tumor.