Got the standard flu shot today and had some slight raised redness. what is really weird is that i also have the same reaction in the opposite arm??

Vaccine reaction: It's normal to have mild local reactions on the same arm where you receive flu vaccine. If there are red spots elsewhere on your body, it is possible that you are having an allergic reaction to your vaccine, and I would contact your doctor, and you can try a dose of Benadryl (diphenhydramine) to see if that helps the rash. If you are short of break or have throat swelling you should go to the closest ER.