Jencycla

I started taking Jencycla 3 ½ weeks ago after being on Yaz. I loved Yaz but I have a history of chronic migraines and the ob/gyn suggested trying a bc w/o estrogen. That did the trick and the migraines are much less frequent. I'm wondering if there is anyone else who has experience with Jencycla because in the 3 ½ weeks I've been on it I've had spotting nearly everyday, some days it's even been medium-heavy flow with cramping. Will this stop after a couple months or do I need to talk to the OB/gyn about switching bc again? I appreciate any thoughts on this! I'm getting really sick of this!