My hair has been falling out and thinning for awhile now, what do i do?

since the 8th grade my hair has been falling out. i use to spike it up but my hair would fall out all the time. i thought it was the gel so i decided to cut it really short and keep it like that for awhile now. but everytime i decide to try and grow my hair out like before it falls out and i can see my scalp with out trying to look. i am 19 now and its just gotten worse. i can clearly see my scalp and even em asked if i am balding. My mom and dad both have really thick hair and are not balding at all. i dont know what to do! i wear alot of hats and beanies since i started keeping it short. can that have something to do with it? what can i do to make my scalp healthy and have hair grow back?