about 10 years ago, i started on metformin. like you i suffered terrible trips to the toilet. it was debilitating and i continued to suffer for more than a year. the only reason i kept going was that i was fortunate enough to work from home. 5 of my aunts/uncles (inc my mum) are diabetic and only 1 can tolerate metformin. i don't mean to discourage you it's like jack said, you just need to keep going for about a month and see whether you can tolerate it.
i am actually now thinking of starting it again to combat my liver dumps. why i would even consider taking it again is that, i am mostly working from home again, that LCHF is already giving me the "runs" but mostly, this time combined with LCHF it actually might help with my FBG numbers.
NoCrbs4Me on this board kindly referred me to this site, which is very informative
http://www.phlaunt.com/diabetes/14045911.php
good luck!! & hope it works out for you.