What Are The Side Effects Of Vicodin 10?

Hi. I have been taking Vicodin 10's for neck surgery and back pain for a few years now. I've been having an allergic reaction to it I believe. I stopped taking it a week ago went to ER for treatment a week ago, blood tests normal, face and neck and chest x ray normal, ct scan with dye normal. Took weeks worth of steroids and antibiotics, got better for a few days, was still taking one Vicodin a day for pain, had 4 beers last Sat, symptoms returned, (itching in neck and face, redness, swelling in face, throat raw) stopped Vicodin 3 days ago, taking 800mg. Motrin and Benedryl . Whats the heck is going on?? I need your opinion.