Brown spotting after Femara

Hello! I called my doctor to ask but they are closed for the holiday. I stopped my Femara on Saturday day 7 and started 75iu of Gonal f injections that same day. I’ve been spotting Brown the entire cycle so far. Today was slightly heavier. I’ve been on this protocol for 2 cycles and have never had an issue. I have a scan tomorrow but I’m worried. Any experience with this?

Thanks!