Hair loss at Age 23: Started after Keratin hair straightening. No receding in hairline, but decreased hair density.

Keratin treatments may lead to hair loss, though this is not always causative. In your case, stop getting the treatment if you are concerned it is leading to hair loss. It is very hard to say for certain without examining your scalp. It is best to consult with a hair expert to medically guide you. Best of luck!

From what you are telling us, it does sound like a chemical burn may have occurred. I don't know what Keratin hair treatments constitute, so your would have to tell us what that entails.