Femara and trigger shot

Brittany
I recently visited my FS and he started me on femara days 5-9 had an ultrasound and I had one follicle that was 19 and he likes for it to be 21 so to take my trigger shot on Monday but today I woke up with pain on my right side and now I'm wondering if I'm ovulating and the trigger shot will be to late?? What exactly does the trio shot do?