Hello~I think that since it is starting to act up again, you should see your GP just to make sure that all is well. I also would take the advice that Sarah gave you, that might help as well.
Hello and welcome to the forum. We're sorry you had this experience. That sounds pretty terrifying! I think if you were healing and it is hurting again and getting red again, it is time to check back in with your doctor. A hematoma can take some time to heal but this was healing and is now getting worse again. Do you still ice the area? This would be a good idea. You also may want to ask your doctor if compression is recommended.https://www.rxlist.com/hematoma/drugs-condition.htm So, check in with your doctor to make sure all is well.