Brain Damage

I still say I think I have brain damage. Perhaps that wording is a little too strong, but hear me out on this.
Ok, I fell, hit my head. Then suddenly I'm all kinds of happy. One theory is that after my brush with death I am just so happy to still be alive that I'm ridiculously happy about little things. Yes, that's a possibility, even very likely, for the first few weeks. Glad I only have a scar. Glad I'm still alive and not seriously hurt. Glad my prayers were answered. Shouldn't that have leveled out by now? I mean it's been almost 3 months.
My theory- Hitting my head the way I did, even though it was not a severe injury did "damage" it in some way. There are correlations between depression and minor head injury. I just read something about serotonin dysfunction after head injury and they only seem to know about people that are depressed afterwards, but what if the dysfunction was the opposite? What if an injury can cause some serotonin dysfunction that makes a person giddy? Acts like an anti-depressant? I think it's very possible. Doesn't explain everything else though. So maybe I don't know what I'm talking about.