What to do for dog with bad allergies?

The vet is more then likely giving her an injection of prednisone which is a steroid injection to help with inflammation of the skin. You can have an allergy panel done on her to clear what she is and isn't allergic too. It can be a little expensive but it eliminates the need for buying and trying all kinds of products that don't work. Also when they do the blood work ask for her thyroid to be checked. a lot of times dogs go undiagnosed and if they are hyperthyroid then they can develop severe allergies and bad skin. She can take benedryl otc but you need to check with your vet about if the injection is a steroid or not because sometimes they do not want a steroid and antihistamine given at the same time. There is also a product called chloryphenaramine which is an allergy medicine your vet can prescribe, and it's very inexspensive. But good luck!!