What Causes Bite Marks On Legs, Stomach And Cheeks?

i developed bite marks on my leg stomach and cheek the pharmacists said it looked like a spider bite my cheek swelled and i went to emergency. they say i have cellulitis and prescribed cephalexin 500mg and sulfamethoxaz on the 3rd day i threw up i ate only a piece of toast for 2 days and on the third day i ate part of a veg and salmon omelet. i have stopped antibiotics as i was taking 7 a day. i feel better but am concerned as to stopping medication. i also take benzapril and a water pill. what do you suggest