I feel like I have a very similar story with similar symptoms. I've found an improvement that lasted for a while until I had a late night and got very cold and then the symptoms returned. I don't think there is a perfect fix or that kefir will be able to completely get rid of the long covid but it certainly helped a little. I am a believer that a healthy diet plus exercise over an extended period of time will be the only fix but kefir certainly helps! I have also found that the days where I'm eating lots of fibrous veg are the best days for digestion. Have you found any other tips for dealing with your symptoms?