Bleeding day after unprotected sex

Hi everyone..

So on the 14th of November I switched off of the NuvaRing to the shot. I kept the NuvaRing in until the 15th. On the 20th of November I had unprotected sex and on the 21st I started bleeding. I am still bleeding. I haven’t had my period in awhile since I was on the ring for a long time. Could I be bleeding because of the birth control switch or could I be pregnant?