My first thought on reading this was "sounds like she's pregnant!" Have you tested, Suz?

Metformin can be fairly evil in terms of side effects - best thing I can recommend for you right now is to drop your dose back. Go back to 1 tablet per day until you feel better, then increase to two tablets again, and then when you have no more side effects from that dose increase, wait an extra week and then up the dose to 1500mg. It may seem like you are going backwards, but there's no point forcing yourself to be miserable and not coping with the side effects. Usually a slower increase does the trick. This is based on the instructions from my rheumatologist and what I had to do to get on to one of my arthritis meds first time around - it's the only one that's safe to have while pregnant, so I was determined to make it work for me, I just had to increase more slowly than normal. The good news was that after the first failed attempt to get on to the drug, when I stopped and then started with much slower (and smaller) dose increases, I was absolutely fine.

Drop the dose back for a bit, and if you then still feel like hell, go hassle your doctor again.

Hope you feel better soon.

BW