sounds to me like u have developed a reaction to your piercing, have u tried removing the piercing and leaving it for a few days and see what happens?
Are the bumps anywhere near the piercing? If so, then the bumps are possibly the result of scar tissue build up as a result of the healing process from the piercing. If they're not anywhere near the piercing; then, maybe they're nodules or benign cysts which sometimes develop in the oddest places in the body... even down there. If they're cysts, and by your description, they could be, they eventually go away over time... sometimes several months. But, if you notice that they aren't going away after a period of time, grow, become more painful, or if you develop more... you may want to have them checked out by a doctor.
By the way, if you had a barbell style stud placed in the piercing, maybe the skin contact with the metal balls is irritating you and creating the bump formation... are these bumps parallel or touching the stud/ ring? If so, it could be that allergic reaction that you mentioned.