Spotting on Letrozole?

Ok so I’m on second round of letrozole for IUI. I had little to no side affect first round. (Hot flashes at night). Today is day 7 of my cycle, finished AF day 5, yesterday I had zero spotting and no cramping. Had sex last night then this morning I have some cramping and brown spotting. Is this normal? Anyone else experience this? I did 3 rounds of clomid last year and never had any issues with spotting. I also did Crinone (progesterone) last cycle planning to do it again once I do my IUI could this all be from that and my body just processing everything? Should I call my doctor?