Is it dangerous to use a straightening/keratin treatment on heat damaged hair?

[Ari-L]

I caused heat damage to my hair, I've lost a lot of it (it doesn't fall out now, I guess it was just pulled out by the iron) it isn't shiny anymore, and it's pretty broken and all different lengths. It's naturally curly but because of the constant straightening (with straightening iron) the curls are coming out. Some parts are curly some are straight so it looks horrible to wear natural. I don't want to continue using the iron but I also can't wear it curly. I was thinking that maybe permanently straightening it in a salon might help because I would no longer do anything to my hair and it may be able to grow out healthier. Would this be a bad idea? I do not want to lose any more hair. If anyone has any personal experience or hair knowledge that would really help! Also, if you could please be specific about the kind of straightening treatment I would appreciate it, thanks!!
I've heard certain treatments, maybe the brazilian treatment? makes hair fall out. I'm terrified of this, if anyone knows which one it is, that would also be a great help!