I have 4 nickel sized itchy welts on my lower legs and bottom of foot. What are they?

Hives. Sounds like hives but could be bug bites, bed bugs, tic bites, or a different type of nodule altogether (erythema nodosum). You really need to see a doctor.
Show them 2 MD. Can't tell here. You need a history and physical exam, maybe labs or skin biopsy. See your doc.