I am not sure why you reacted to kefir all of the sudden. I must say that I also thought I had a reaction to it as well and made like a month break from it in January. It felt like my body has had enough of it or something, hard to explain. Then I started back on it slowly a month ago, one cup at a time. Now I’m up to two large cups per day and mostly I am fine, but it seems that my throat lump/tight throat is back for some reason. I do not feel any heartburn, didn’t have any for months now. I did start back on more lemons also so it’s one or the other. I will get rid of lemons for few days and see if it improves, I really do not want to stop drinking kefir.
I did change my milk as they reported the one I was using had some kind of toxin in it or whatever. They cleared the current supply of this milk so I am switching back to it as it is really the best I can get in the bottle. I am trying to find a safe raw milk supply but it’s hard. Maybe the milk you were using has changed for some reason? They do this from time to time. Or it could even be something cows were eating (rarely they are grass fed) that was bothering you from milk and if it’s not bacteria, kifir grains will not get rid of it.
Let us know if goat milk kefir is also giving you reaction.
Best of luck to you!