What Causes Spotting Inspite Of Being On Provera?

I have pcos and have been ttc for 2 years. I had a hsg test done on Dec 29th CD8. I don't have regular cycles. The last two cycles where started with provera. On Jan 16 17 and 18 th I noticed that when I wipe there's pink on the toilet paper. Could this be implant bleeding? It wasn't pink all day just a one time thing on these 3 days. My baby chart says I ovulation on the 10th of Jan. I thought it was my menstrual cycle starting but this has never happend before.