What's wrong with my hair?

I am a 17 year old Haitian girl. I used a relaxer since i was about 11 years old. Ever since that, my hair has been breaking off. So when i was in the 7th grade i cut my hair short (fantasia style). The middle of my head has always been the shortest and it would always hurt every time you pull or touch it. Now I%26#039;m gonna be a senior and my hair grew back a little bit but the middle of my head never grows and it still hurts. Also im starting to loose more hair in different parts of my head. My doctor told me to use head and shoulders for 3 months but that didn%26#039;t work. Can anybody tel me what to do please. My mom don%26#039;t want to send me to a hair salon again (it started getting to expensive) PLEASE ASAP!