So confused!!!

I’m currently CD10. I had my baseline CD4 and they found a cyst which bloodwork had confirmed was estrogen producing. The following day I had a trigger shot to trigger out the cyst. They said 12-14 days I’ll get another period. Well....here I am with what appears to be my period??? Not just spotting, like an actual flow. And I guess I’m not surprised because my breasts have been very tender and I’ve been getting bad headaches for 2 days which are common PMS symptoms for me. Is this common to happen?? I was supposed to have an HSG test Tuesday but I’m guessing that’ll have to be cancelled and I’ll have to my baselines again?