I agree, it sounds like you have an infected hair follicle. If it's been there three months, it might be a good idea to have a doctor take a look at it to see if it needs treated. If it's getting reopened a lot though, it may be the cause of it not healing. Can you wear loser fitting under garments? That may help. Also, not picking at it. You may try using some cream like Neosporin or a healing balm on the spot too.