I have a bite on my leg that started out itching today., now has a bruise around it that's painful to the touch and is a little swollen. Suggestions?

You must see a doc. Bites can be from animals (cat, dog, other), humans, tick, spider, insect, parasites, etc. They can be simple or potentially serious. You are describing a possibly infected bite on your skin. Preferably sooner than later, you must have a healthcare professional look at the bite mark and determine what treatment, if any, you need. Also, you may not have a bite but something else that needs eval.