First time sex after miscarriage - can I get an infection?

So I miscarried on the 9th of September and stopped bleeding around a week ago. Yesterday I felt ready to be sexually active again with my husband and we even did it twice. Right after I started having brown discharge and even today (looks like old blood). That didn't worry me much but today down there it feels a bit irritated. Could it be I got an infection? Is that normal after a miscarriage? Or is it because we haven't had sex in a while? (Around 2 months because when I was pregnant my gynae suggested to avoid sex the first few weeks)

Thank you.