Poor Matthew, I hope he gets better quickly!
I had to take some Zithromax about a month ago, for a sinus/throat infection. Worked good, but it did have some side effects (to my digestive system, urgh...)
That's what I'm thinking. He drank down that first "double dose" which was a very sweet liquid and then rinsed it down with Sunny Delight. Not a good combo imo. He's absolutely fine now and I think (could just be wishful) that the actual ring rash around the bite is slightly lighter.
He's got a ring with two "tentacles" shooting off of it around the bite. Really weird looking.