Trish,
I would suggest a few things for your condition. One thing I would definitely recommend is to find a La Leche League group in your area to become familiar with the Leaders and meet some mothers who are giving their babies breastmilk. Mothers who exclusively pump have special challenges and are very welcome at meetings and you could probably use the support.
The Breastfeeding Answer Book says, "Breast abcesses happen rarely. When they do, they are usually the result of untreated mastitis, a delay in treatment, or incorrect treatment. The abcess-a localized collection of pus-forms in an area of the breast that has no opening for drainage and so it must be surgically drained to the outside. It is a serious and painful condition that needs immediate medical attention."
Sometimes your doctor can confirm the abcess by exam alone. Mammogram does not calrify the difference between abcesses and other masses. Ultrasound preformed by an experienced tech familiar with the lactating breast has been found helpful though in distinguishing abcesses. If the location of the abcess can be confirmed before attempting drainage you can avoid unnecessary incisions in the breast. Breast tissue is very delicate and the tech and doctor should be gentle with it so as not to create further damage to the breast.
"A breast abcess requires surgical treatment with antibiotics and rest, but in most cases breastfeeding can continue." You can definitely nurse on the unaffected side and if the baby's mouth (or pump in your case) doesn't touch the incision you can nurse on the affected side. This will not prevent healing.
As for the mastitis, antibiotics alone will not elliminate it. You have to do some things to remove the clogs (to prevent further abcesses). First, you have to REST! This is extremely important. You need to massage, a lot! Do this about 8-10 times a day as often as you think about it. Use as much pressure as you can stand. Sometimes it helps to use the back of an electric toothbrush or a comb to massage too. Start at the clog and massage out toward the nipple. You may see some of the clog coming unclogged, might look like a thin strand of spaghetti, might look a little like pus or thick milk, could be yellow, have a tinge of pink, red, or brown. This is all normal and okay, just a little blood and won't hurt your baby, no need to discard it. Apply heat to the breast before feeding/pumping and massage to help loosen clog. Nurse or pump on the affected side as much as possible. Vary nursing positions, baby will remove the most milk from the area in which his nose or chin is pointing. High doses of vitimin c are shown to help (5000-6000 mg of high quality c like EmergenC brand) until you reach bowel tolerance. You really have to do all of the things to make sure it goes away and doesn't quickly return. Hot showers and baths can help also.
If it is truly an abcess the lumps won't go away and won't lessen. I would have an ultrasound like the Breastfeeding ANswer Book suggests to confirm. It will take several days to get rid of the clogs so you need to take your baby and go to bed for at least the weekend, stay home and away from sick people (this contributes to clogs), avoid added stress, rent some movies and order in. I know it is a holiday weekend and there may activities planned but this is more important to take care of!
I would also suggest avoiding all dairy. Because of the hormones and anitbiotics in it our bodies response to that is the manufacturing of pus cells. This causes sickness and seems logical that since an abcess is a pocket of pus you might be better off not consuming it.
Also, if you need to have a medication checked you should call a LLL Leader to look it up in Medications and Mothers Milk. Almost all medications are fine but sometimes doctors tell you to pump and dump without reason.
Heather