hi roshni, sorry to hear you had a scare and worrying advice from your doctor. It seems to me that many medics suggest mums stop breastfeeding simply because they don't know enough about it - and can't control it either.
When ds2 was in hospital after a serious infection the nurses had obviously been told to measure how much he was taking in, and kept popping in to ask me when I last fed him, and how long he had fed for (as if that is a good indication). It appeared to be a problem for them that they couldn't say 'at a certain time he had x ml of milk'. I also had dietitians and doctors suggesting that I should try him on hypoallergenic formula (we have food sensitivities in the family) when I was perfectly happy to avoid foods in my own diet rather than feed him what is by definition an artificial food.
Anyway, this doesn't directly relate to your questions, but I believe - and La Leche League would probably have more information - that there are extremely few situations when you really need to stop breastfeeding. I used to think that two of those were when the baby has phenylketoneurea (PKU) or the mum has HIV. The information on the La Leche League International site seems to say that even in these situations, it is not clear that stopping breastfeeding is the best course of action to take.
If, now or in the future, you are worried about the effect of any drugs you may have to take, the Breastfeeding Network has a helpline called drugline specifically dealing with drugs and breastfeeding.
Also, it might help you to find a La Leche League group near you. I only occasionally go to the meetings, and I find their set-up a little strange to be honest, but when I do, it is hugely encouraging to sit in a room with perhaps 20 other mums all breastfeeding children of various ages (from a few weeks up to about 2 1/2 yrs old last meeting I went to) and to talk about the day-to-day realities of breastfeeding with people who are definitely not following the recommendations found in so much of the books and other media aimed at mums nowadays. Plus I have found their helpline truly helpful, particularly at the time when we had pressure to wean ds2 onto solids early (again, despite food sensitivities) and when he was in hospital, as I mentioned above.