I got stung by a yellow jacket and it is getting really bad, i don't know what to do?

it stung me on the back of my arm by the armpit, now my whole arm down past my elbow on the backside is swollen. It itches really bad, it burns, and the swelling is making the skin so tight that it hurts really bad. I have tried baking soda, aloe, banadryl, bactine, ice, and nothing seems to do much good for more than ten minutes or so. It has been a day and a half and the swelling keeps spreading. I dont have medical, and i would feel really bad going to the hospital if I dont need to. Is there any other suggestions of what I can do to make it feel better?