I got a bunch of fly bites the other day that did pretty much the same thing. At the time I didn't even think they were biting - I only felt one or two, but the next day I woke up with my ring finger all swollen (I had to grease my rings off) and about a dozen or so more super itchy, raised bites. They itched horribly and were all bumpy for a few days. I took some Allegra and used antihistamine cream on them to take the edge off. They stopped itching after about 3 days and the swelling went down after about 4, but the red marks on my legs lasted almost 2 weeks.