Hun, it really should clear up quickly with ABs. I've never had the fever and ill symptoms last for more than 24 hrs once on ABs.

Have you tried an anti-inflammatory as well? It might help reduce the pain and inflammation around the lumps. Don't massage too hard either, gentle stroking in the direction towards the baby while feeding. Ice packs on the sore areas after feeding will also help. Try bfing in different positions (football hold, crouching above the baby on all fours, lying down) to clear blocked ducts as well. I would avoid expressing in favour of feeding your baby if you can, he'll clear it much better than a pump or by hand.

Do you think there might be something else going on as well as mastitis? Have you had thrush? It is probably worthwhile taking a probiotic as well while you're taking the ABs.