500 mg of metformin.

Jaimee
So I have pcos. Was diagnoced when I was 16 and I am now 23. I started taking metformin 4 days ago. I have lost 3 pounds already which is awesome. 
I guess il start with my cycles are usually 35-40 days long. Currently I am on CD21, and I have had brown/pink spotting for three days. 
Yesterday I took an ovulation test and it had no second line, what's so ever. Today, I had a second line that almost seems like it could be positive either later tonight or tomorrow. 
Is it possible to have bleeding with ovulation? Especially for three days? Also would metformin work this quickly? 
Below are pictures of the ovulation test from today; and my bbt chart. I stopped temping for a while and just started back up with it a few days ago, so I know it could be hard to read.