Not sure what's wrong with me? Epilepsy?!?

Last year in April or early May I got hit on the back of my head on the left side. I was told I had a concussion. I woke up early the next morning with vertigo and nausea and my mom took me to the ER. I had a CAT scan but there seemed to be nothing wrong. It's about 7 or 8 months since then and I have noticed a few things during this time. I know after I got hit I had memory loss and I lost 300 dollars and still can remember it ever happening. Lately, I have been getting lightheaded and dizzy which causes me to become nauseous and have an upset stomach. It's not severe, just mild or moderate. I have also been getting headaches and this funny pressure feeling in my head ( I can't really explain it), but only every once in a while. Also, ever since I got hit in the head I have been having a comprehension problem and math seems to be a lot harder than it used to be and when people explain directions to me it takes a few tries to fully understand it. For example, my teacher asked me how many seconds were in a min. and I could answer it. Weird right? I got so frustrated. And also, I think part of it was I didn't know what he was asking, like for 2 seconds I blanked out and didn't hear him almost. I used to be a great studentt with A's and B's but now I'm getting D's in math because I can't understand and retain it. Also, I have been having lots of mood swings, like I will get angry out of nowhere and it makes me feel really bad so I get depressed. Along with that I have these disturbing thoughts about death and different things which really freaks me out. And most of all, every once in awhile I finding myself caught in a blank stare as if zoning out but I'm not thinking about anything and I don't remember anything that happens during it and it even happens when I'm driving. I'm not sure if it is a seizure, like simple partial seizure. My friends will catch me staring at then but i don't even know I am and I snap out of it. And the most freaky part of anything I have experience is I smell random odors that aren't there. Like my mom has caught be spraying air freshener because I think it smells so bad but it doesn't smell like anything to her. Also smells also seemed to be enhanced, like I have a really good sense of smell. And I don't know if this is related but I have neck stiffness when I sleep and my lower back hurts sometimes, but that might be just because of my bed. If you can help me find out what is wrong I would be so thankful. I'm so worried.