I fell and hit the back of my head on concrete 2 days ago have a bump and small scrape but has been going down almost no bump now i've been having slig?

Slight what?: Your question got cut off, so i don't know what slight thing you're experiencing after you fell. If having any symptoms such as headache, dizziness, forgetfulness, irritability, nausea or vomiting, etc please see a doctor.. You may have a concussion, which will heal on its own. A blood clot forming on the inside of your skull would produce more serious symptoms, but would be possible also.

Concussion: You fell 2 days ago and have a healing bump on the back of your head. You have headaches. This could be a concussion. More and more research shows concussions occur during head trauma. See your doctor and you may require a referral to a specialist.