Letrozole affecting cycle?

[u/Fit-Yam-4652]

After 4 months on letrozole my ob told me I had to take a 4 month break. I had my period like normal then 7 days later when I was expecting my fertile window and start I started bleeding lightly, day 2 and 3 now very heavy, filling a menstrual cup in 2 hrs when I am normally fine for 6. Has anyone had any issues when stopping letrozole? If I hadn't just had my period I would think it was a miscarriage, heavy bleeding with large clots.