LEAVE IT ALONE! By all means, do not try to pop that pimple. Even if it does pop, I guarantee you that another one will appear in the same region. The bacteria spreads in the dermis, especially by your mouth because the skin is so delicate there.

You can ice it, put some alcohol or hydrogen peroxide on it plus a spot treatment of your choosing. Also, taking an NSAID (advil, etc) can help with some inflmmation. Unfortunately the best thing to do is just leave it alone and hope it goes away soon!