sore bicep from yoga

My left bicep has been sore for about three weeks. I have been doing a lot of yoga – the bicep really hurts while coming into chatarunga – which is lowering from straight arm plank to pushup (with elbows tucked into the sides). From there, we usually bring the body forward without letting it come down to the ground before pushing into upward facing dog. The arm hurts a bit when I push on the muscle, and it really hurts when I attempt to do the action described above.
My questions are: 1) is this a strain? sprain? pull? 2) how long should I abstain from yoga?
I feel like sometimes I can go and it feels better but I don’t want to make it worse 3) is there anything I can do to help it heal? Thanks a lot.