Depends whether it’s the tendon or the muscle. Sounds like you first need it to give it a few days to calm down.
If you’re feeling it up near your ass or right behind your knee, it’s probably the tendon. In the middle of the back of your leg, the muscle.
If it’s the tendon you want to lightly stretch the muscle so it doesn’t tighten up and put too much tension on the tendon. If it’s the muscle you just have to rest it.
Most of the elasticity is in the muscle, not the tendon. So when you do stretch, you want to feel it in the muscle belly. If you’re feeling it near the joints, you’re doing it incorrectly and you want to make adjustments.