My arm is swollen

i got accidentally stung by a bee yesterday. It didn't try. In fact it could be said that I stung myself. The bee was on the back side of my forearm, and i didn't know it. I then put my arm down and smashed it's stinger into my arm. I now have a big swollen sopt on my arm that is like 3 inches by 6 inches. i wouldn't recommend getting stung by a bee.