Guys hairloss

I have a straight line in back side of my head idk it was never there. But now I have it I'm concerned if I will go bald . Because I can see my scalp my hair has thinning and it used to be thick but not rn. What should I do my parents say I lay in my room that's why and I use phone

I'm 19m and I don't have money to visit a doctor. I'm pretty desperate.