Metformin giving lower abdominal pain

Has anyone using metformin had bad pains in the lower abdomen that sometimes shoots through to your back? I've been taking metformin for over a year now but it was on and off and now I'm starting to take them continuously so I don't know if maybe it's my body just getting used to it and it's just gas pains or what, it's mainly in the lower left side. Any insight would be very helpful, thank you!