What is this unbelievably itchy sore?

I've been taking 50mg of Iodoral for 6 weeks.  I suddenly got this "bite" type sore on the back of my thigh that is so itchy it woke me from a dead sleep.  I don't usually react to mosquito and ant bites, so I believe that this is something very different from a bite.  Could this be the iodoral overload reaction?

I've also posted this under the parasite forum because I started Colonix with Paranil two days ago.  The sore appeared about 12 hours after my first dose of Paranil.  Could this be a creature trying to get out?  I don't see anything, but it's becoming rather swollen.

Please help!  What do I do?  It's driving me crazy!  One or two more sores like this and I'll be insane!