Metformin side effects

So I have a couple questions about metformin. I was told i have pcos about 3 months ago and I started metformin about a month ago and I have felt like complete crap and I feel like it is giving me the exact opposite effects it's suppose to. My appetite has increased, I have gained 5 or 6 pounds in just a few days and I can't go to the bathroom until my stomach is absolutely killing me which is like every 2 days? I'm only taking 500mg once a day and I have thought about stopping it quite a few times. I am in my tww now and I go back to the Dr on Friday so I will be talking to them about it then but has this happened to anyone else? I'm kinda concerned because it just doesn't make sense. Any ideas would be appreciated.