Small hematoma?

Hi guys, I spent basically all of yesterday in the ER for an allergic reaction to the covid vaccine. Difficulty breathing and a massive rash on both arms that will not go away. When I was there they did an ultrasound to check on baby and said everything looked good but there was a small hematoma. Has anyone been told they have had this? How do they treat it? What should I do? Should I be worried? This is my first pregnancy. 🥺❤️