K.H.
I hope this problem has resolved - it is already Tuesday. But if not, consider asking your doctor to find a drug that is compatible with breastfeeding or call back and make sure that you need to dump the milk. You could call a lactation consultant who would have access to books that describe the side effects of particular medications and the amount that passes into breastmilk so that you would have more information.
It is really tough to be sick and have an unhappy baby to care for. Keep up the pumping as sudden weaning is really tough on your body. You may have better luck feeding the baby with a sippy cup.
Get well and hang in there.