I hit my head very hard falling down the stairs lastnight and have a huge lump on the back of my head, I had a massive headache , a little dizzy, nauseous, and was a little slurry with my words. I went to sleep and woke up and the lump has gotten a little smaller and my headache has gone away, am not nauseous, speech is normal but have a little blurred vision . Should I see a doctor or am I alright and what is wrong? When I hit my head I blacked out for a second