Is my belly button infected?!?!?

I've had it pierced about 3 1/2 months, and I haven't had a problem with it until yesterday! I got a new belly button ring (surgical steel) and I have changed it quite a few times, and this one it just doesn't like. The top hole is so sore it's almost unbearable to touch, I can't even lay on my stomach without it hurting. There's like a little bit of wetness around the hole, it's swollen, and it's red! If it is infected, what do I do to make it not so swollen & not hurt so bad! And heck get rid of the infection..