My father (age 71) has been diagnosed with cellulitis in his arm 5 times in the last 5 months. i have to believe it's something other than cellulitis? does anyone get it every month? he was treated with antibiotics each time. what else could it be?

What bug/ treatment and for how long? Would check his CBC. immunoglobulins- if somewhat immunocompromised that could be a factor, check for lymph nodes( lymphoma).. Would also check if he has a recurrent source, is there something he is doing that exposes him to recurrent infection. At times even pets are the carriers of infection . Does he have any implant in his arm? f/u/ w/ infectious disease