What Causes Large Bump On Outer Labia?

I went to the ER today because i have a large bump on my outer labia they prescribed me cephalexin 4X day for 10 days. I have also spent the whole day putting warm compresses on it. It is still really painfull and i dont think it is actually "coming to a head" my question is how long does this antiobotic take to work to shrink it. Im going to my gyn doctor in 3 days will he have to do a surgury? will it hurt? would i be able to go back to work? and how long does this take to heal? Im suppose to go on vacation in like 7 days and this is awfull timing.