Did I damage my voice? Can I fix it?

I was in a musical theater cl for 3 months, and then in a rock band for about a year. I constantly belted in these situations. I know I was using the wrong technique, because my throat hurt and my voice cracked. Now, whenever I sing in the middle of my range, my voice will randomly slip and make a kind of croaking sound. I have to sing quietly in this range and can't crescendo at all, or else my voice slips. Did I damage my voice? Is it permanent damage, or can I fix it?