I have no side effects anymore, except maybe to have to go to the toilet 2-3 time each night.. which started when I was put on metformin... but metformin is known to cause bloated stomach... I had that the first 2 weeks, then it disapered...how long have you been on metformin ?
if your sugar isn´t under control like almost normal the raised sugars can in worst cases affect stomach nerves as well like some are hit by neuropathy, one can get these problems all over in ones body...