Can craniotomy (incision ear to ear), cause hair thinning 5 years post surgery?

I have recently noticed that the hair on my head is much, much thinner than when I was younger. I had craniotomy 5 years ago, where my whole scalp was pulled back. Ever since the surgery I have experienced pain in my scalp(whenever I bump my head) as well as a dryness and itchiness. Just recently however I noticed that my head hair has become quite thin and falls out regularly. Could this be due to the surgery? I am 24yr old Caucasion male, no baldness on either side of family.