Why does this rash keep coming back?

Andrew is a 40-year-old miner. He presents with recurrent rash over the past year.
He has seen several GPs but has not had time to get it investigated further.
He reports itchy, red scaly lesions, often in his axillae, that blister and then weep.
He has previously been diagnosed with impetigo and feels antibiotics have helped, though is concerned about the frequency of use.