Suggest Remedy For Recurring Abcess On Buttocks Area

hello, my boyfriend has got another abcess that has returned in a similar place he had a previous one. The abcess is located between the bottom off the spin and bum in a very sensative area. He first had one 3 years ago which required surgery, he had to have the hole packed for several months after and he has had a few little ones since them but nothing as nasty as this one now. He has just finished taking antibiotics to sort it out but to our horror in less than 4 days its has gone worse than ever, there is a lot off blood and were gutted its turned out this way. Could this be all linked to the antibiotics and is there anyway we can stop it coming back? I would appreciate box help or advice, thank you