Early period on Femara?

Br
I am ttc my second child. I was on clomid for 10 months with no luck and now on my second round of Femara. Day 1 was November 5th. Not a full period but OBGYN told me to count that as my day one. I took Femara days 5 to 10. I had my ultrasound on day 15 and was told I had already ovulated. Today is day 22 and I have had spotting throughout the day, and mild cramping. I normally have a 40+ day cycle. Anyone else experience this on the high dose of Femara? Wondering if it's normal or if I should give my doctor a call in the morning.