Patrick
You failed to mentioned your husband's age, the area oof the leg struck, how big the branch was, and how he is doing now, but from what you have mentioned is that swelling amounts to fluid in areas where it is not supposed to be. Also, yellow signifies old wounds as red, and black and blue signify fresh wounds. The possibility of fractres to the fibula and/or the tibia along with muscle tissue, and arterial damage amonts to cover the things that you are seeing on your husband's leg. My strongest suggestions is to activate your local emergency medical services and get your husband to a medical facility to recieve the proper tests and treatment to alieveate the swelling and pain that he is experiencing. Good luck to you both.