I bumped my head on a wall a month a go and i still have the bump on my forhead. what do i do?

Likely nothing: If the bump appeared at the time of your injury it is likely a simple hematoma, mild bleeding under the skin. The majority of the time this resolves relatively quickly. Sometimes, however, the blood organizes almost like a scar and takes longer to be reabsorbed by the body. It is not anything to worry about medically just more of a cosmetic issue. It may take months for complete resolution.

See your doctor: This is a problem that necessitates a face-to-face meeting with your doctor. This will allow him/her to examine you, ask specific questions. And possibly order tests to find out what's wrong and what to do to help you.