You might find that you still have milk after a week. Boobs that reach toddler feeding age can often be quite adaptable, and will bounce back.
I have stopped for a week twice while being away when DS was around two, and gone on to continue with 2-3 feeds a day for almost a year after that. I never expressed, I felt a little full but not uncomfortable - so you might be ok after a week if you still want to feed after the medication.

Hope you are feeling better soon.