LOL. I remember how bad I felt the day after (in fact the entire week thereafter) I drank a whole bottle of whiskey one night when I was 18, I would have felt a whole lot better if I had a few shots and enjoyed the experience, instead of overwhelming my gut, brain and liver - and paying the price for days thereafter. There is nothing like personal experience! NOW you know how kefir affects you, respect its action, it probably has the potential to do you a whole bunch of good - is small regular doses.
Whenever you take in something new or a food/drink with the potential to make you feel really good, good advice is to take it real easy. That way you will be able to measure the response and take more or less as required. Shame marriage isn't like this. lol.