Suggest Treatment For Recurring Skin Infection In Elbow Causing Redness And Swelling

My husband has been experiencing some kind of recurring skin infection which started up again yesterday. He has tested negative for staph. Yesterday morning his elbow had a small (pin-head size) mark that almost looked like the beginning of a mosquito bite, surrounded by a red area, about the size of a quarter. 8 hours later his entire elbow was red, slightly swollen, and warm to the touch. This morning we woke up and the elbow is still very red and warm, very itchy, and there is a red line about 1 cm wide that has snaked around his bicep about half way up to his armpit. He has been on antibiotics before when this has happened and they don t seem to have helped. He acquired c-difficile back in the spring as a result of taking antibiotics for suspected cellulitis so now he is extremely wary of taking any meds. He is an otherwise healthy 38 year old man, not on any other medications or even supplements.