Belly piercing issue! please help!!!!?

i don't know what it is but every time i put a surgical steel belly ring in, the bottom hole hurts. Like it feels like a stinging sensation. I've had it for 2 months. when i was finally able to change it i put in a plastic (bioplast) ring, and never had any problems. then i put in a surgical steel one and after about a day it started to burn! I don't know what the issue is because THE SECOND i put the plastic in, its fine. Help?