Pregnant. Numbness In Pelvis, Painful Big Lump On Groin. Prescribed Flucolxacillin. Safe?

I had a lump on my groin / bikini line and went to see the gp about it 2day. It wasn't particularly painful but a bit worrying. Also my pelvis is starting to feel numb (like a strip of numbness) coming from the general area of the lump or slightly lower. This appeared on Thursday and numbness has grown in size from what feels like a 10p coin to the size of a tomato. The feeling in my leg is worse when i walk, try to climb stairs. The doc ,who was great , prescribed me flucloxacillin and asked me to return for a check up on Wed as it was quite a large abscess. My concern is that I am 33 1/2 wks pregnant and really don't want to take any other medicines. Am I putting my baby in any sort of risk, as insert says be extra careful if pregnant or breastfeeding. Also am I putting myself at risk if I choose not to take them, ie poison entering the bloodstream which would affect baby too?? Can i wait til after baby arrives? Many thanks.

Lynsey