I got bit at least 20 times on my legs. some are starting to swell and obtain and red round ring around the bite. they are very itchy. what is this?

Infected bug bites : you've probably been scratching your bug bites and now they're infected. I suggest warm compresses, applying an over-the-counter triple antibiotic ointment like Neosporin, and stop scratching. If the redness gets worse, spreads or if you have a fever, you should be seen by a doctor

Poisonous bite: Clean the area daily and apply local antibiotic. If you are in deer tick infested area see your doctor soon.