Hi Flowers
Do you really need to stop breastfeeding? Most drug companies don't license drugs for breastfeeding mums because the market is so small it's not cost-effective, but that doesn't mean that they aren't safe to take. There's a really good table to check the particular drug you've been prescribed here: https://www.kellymom.com/health/meds/aap-approved-meds.html
If you find that the drug is contra-indicated, then maybe you could have a different antibiotic? Usually there are choices over the type of drug, and also over the route of administration (which also impacts on how safe it is for baby). You might find that a short acting version of the same drug would be safe to take, for instance. How old is your baby? A very small baby takes only minute quantities of milk, so hence, very small amounts of the drug enter the baby; a toddler normally has a variety of other foods so the amount of milk is also small in comparison to body weight.... it's rarely a clear-cut decision as to whether or not you need to stop BFing.
If you do decide to temporarily suspend BFing, then the general rule is that you need to express as often as baby would have fed. The exception to this is with a very young baby where you are needing to build your milk supply. A hospital-grade double electric breast pump can be really useful; you may be able to hire one from your local NCT or similar.
Why don't you call the National Breastfeeding Helpline to discuss? 0300 100 0212.
Mel