What should i do if i'm having extreme pain from my permanent retainer?

Unusual: It's very unusual to have "extreme" pain from having a permanent retainer placed. Call your dentist, explain your problem, and ask for advice. In the meantime, you can take some otc pain medication such as you would for a headache (motrin, advil, aleve, (naproxen) tylenol).

Very Unusual: This is a very unusual question. "permanent" glued OM retainers are passive wires glued to the back of your teeth. Only thing i can think of is that you might have bent it on some hard food and it is moving your teeth. Go see your orthodontist asap.