How can i tell if i have brain damage?

like I've done some crazy stuff the past few months, but like the past few day I've been forgetting a bunch of important info maybe its because I'm burnt out from school and have finals in a week. My performance rly hasnt been affected, but i've turned into a total idiot like losing stuff that's in my pocket, forgetting obvious stuff, etc. I also did the most terrible job i've ever done in a chem lab and couldnt even find equipment right in front of me durrrrrrrrrrr. >_<