If its been 21 days since i first had covid and a few days since ive had any symptoms and ive missed my period. my stomach starts to hurt does that mean inflammation from covid? is new inflammation due to covid that possible at this time?

It is probably not COVID. You did not indicate for how long you have missed your period or it is probably just delayed. The more likely symptom this far out for COVID 19, may be feeling tired and probably still some cough. I hope you pay attention to what you are eating, if no vomiting nor diarrhea you may just watch and wait for a couple of days.

It is common to miss or to have a delayed menstruation cycle with a recent illness. I agree watch for signs of vomiting, diarrhea and fever. If moderate pain or focal abdominal pain develops, please see urgent care.