I have a little bump or lump on my cranium behind my head on the left side that comes and goes and hurts a little when I press on it its inside my head and doesn't seem different from the right side its just a bit bigger and hurts to touch .its about five fingers from the left ear on the cranium where the head changes shape ... please help me I've been getting this at the same place every once in a while since I'm young and now I'm pregnant and looking for answers , thank you