September 29th, 2016, 06:31 PM
Welcome to the forum!
In this situation, I would definitely just breastfeed the baby. A week off from nursing is not something you want to do unless you must- too much misery for both mom and baby, too great a chance that the baby will decide that he's now a bottlefed baby and doesn't feel like nursing any more. This is true even of babies who have always had an easy time going back and forth between bottle and breast, because there is a big difference between getting bottles part-time and getting them exclusively for days on end.
The risks of antibiotics to the baby are minimal. At the very worst, you would be looking at some diarrhea due to the baby's gut flora being perturbed. But even that is not a given as the quantity of antibiotic in your milk may be too small to bother the baby's digestive system. Also, as far as I know it is not true that it's better for a baby to build his immunity without antibiotics. Immune system development is a complicated process, and I have never seen any evidence that short term, low level exposure to maternal antibiotics does anything to a baby.
If you're still not convinced, then yes, it's okay to use up that stored milk provided proper storage guidlines have been followed. The milk is just as nutritious for a 6 month old as it is for a 6 week old. I know there is a lot of chatter about how milk adjusts to meet a baby's needs, but the changes in composition are dramatically overstated. You can safely feed milk...