Brown period?

So I’m 26 and I’ve been on the pill for 12 years. My periods have been normal and haven’t had any problems. I went to my dr to see if they could get me a solution for my adult acne (which is very annoying) and he prescribed me Metformin. I’ve never been diagnosed with pcos before but I have been on spironolactone. Apparently Metformin is not just for diabetes (which I don’t have) but I took it for 3 weeks. Then my period came a week early. But it wasn’t my regular flow or color. Just brown and light, but enough to need a pad constantly. This lasted for 10 days! My periods are usually 6 days and the normal red. So I freaked out and stopped the Metformin. So 2 weeks later I start this “period” AGAIN! I’m on day 10 now and it doesn’t seem to be letting up. I asked my doctor about it the first time and he said the meds make your hormones unbalanced until your body adjusts. I’m just weirded out and am not going back on the Metformin. Also benzoyl peroxide 10% gel seems to be working much better. Any one else have an experience like this?