Cycle changes on metformin?

So I started metformin at the beginning of this cycle. Normally, I’m regular. 33 day cycle. Had spotting cycle day 19 which is when I should have ovulated. Now, at 8 dpo (period 6 days away) I have more spotting and cramping I think it may be AF coming 6 days early WTF.

If you started metformin did your cycle length change?