Spotting v. Period + cyst after failed IUI

[Anonymous]

Curious if any of you have experienced something similar and what you did as a next step. Here’s the situation:
34 yo f w/ secondary infertility
Finished 3rd IUI cycle w clomid
Negative pregnancy test 12/23
Super light period started 12/26 (brown...not red)
Day 3 u/s showed large cysts and bloodwork indicated I was still in the “pre period phase” (the nurse’s words)
I’m thinking it may be time to switch to letrozole? Particularly since I have a history of PCOS (though ovaries have not shown cysts from the time i was preg with #1 until now)?

Anyone have a weird spotting type period as opposed to normal flow? I had been so regular even while on clomid.