hello and welcome to HCM Your father has probably developed a condition called hidradenitis suppurativa, which affects the glands in these folds, esp armpits, groin,etc. This condition takes a long time to heal and also can be very recurrent as it affects deeper tissue. As they keep healing and coming back the skin becomes thicker and makes movement difficult. Also causes recurrent infection in the area. I would advise you to get it looked at by a dermatologist to confirm this diagnosis.A culture test of the pus should be done and if possible a biopsy of the area to rule out other diagnosis. He will require a course of antibiotic tablets as well as to continue the ointments, but only to clear any infection present. The underlying problem may need further treatment like steroids, injections and certain higher drugs to be prescribed by your doctor. If the sores and lumps are very large and oozing, surgical opening may be done and any deep lesions can be cleared to prevent them filling up again. you may be referred to a surgeon for this. Presence of certain other illnesses, family history and smoking can aggravate it. I would advise you to consult the doctor as advised with this diagnosis. A biopsy will help rule out other similar conditions as well. Hope this helps.