Hi,

what I'm wondering is, what did the doctor suggest you do about it?
It is probable that the antibiotics have caused some mild damage to the gut, leading to the bleeding. It may even be a little secondary lactose intolerance as a result of this. However, the only treatment is to keep breastfeeding your baby. It will heal with time. It would absolutely not be recommended that you interrupt or cease breastfeeding. Your coctor is right - if there is not pain or discomfort then just time will heal - it's not a huge problem.
BTW, many mums don't realise that babies naturally cluster feed in the evening - our bodies make milk the same day and night - but babies are irritable in the evenings and want to feed lots - it cures all sorts of ills - from grumpiness to boredom and more.
All this is worrying and confusing it's good to ask the questions