Hi, E.. I had to stop breastfeeding without any warning when my son had just turned 1 year old because I had to go on medication that could have harmed him. We actually made a fairly smooth transition, although it was hard for a little while. Basically, the day that I found out I had to stop immediately, I sat down with my little son who was used to crawling up to me and happily latching on. I told him gently, "No, we can't do this anymore," and I wouldn't let him nurse. He cried for a while as I soothed him -- I gave him a little time to express his confusion and hurt feelings -- and then I offerred him a bottle, which I gave him while I held him close and soothed him. He made a quick transition to the bottle because I was still holding him close while he drank from the bottle, and he didn't lose any closeness with me. I felt awful at first, but I would have felt much, much worse if I'd allowed him to drink my breast milk full of medicine that would have harmed him.
I think if you have been giving him relief bottles up to this point as well as breastfeeding, he will make a better transition. And if it's for your health, please don't allow yourself to feel guilty about it because if you don't take care of yourself, Honey, you won't be able to take care of your son, either.
Peace,
Syl