Metformin side effects

Hazel
I've recently been prescribed metformin 500mg 2x per day. 
I've got PCOS and not diabetic so it's for TTC but the side effects are hitting me bad. 
It's only been a week and I'm having to take Imodium several times a day and today I started vomitting 
I was warned runny tum would be a side effect but I didn't think it would be this bad. 
Does it get easier or should I be talking to my dr considering I've progressed to vomitting? 
I've been TTC for 3 years so don't want to give up if I don't have to.