Yes, your concern is very true. In my clinic, I first advise blood sugar level for such chronic cases & if diagnosed as diabetic, strict sugar control is achieved with inj. insulin. In you case, it looks more like carbuncle. To my patients, I advise X-ray to rule out any deeper extension. Depending on size, spread of swelling & patient fitness, I take patient in operation theatre for complete excision of swelling under anaesthesia, leaving behind no cyst wall, a cause of chronicity. Post-operatively antibiotics, pain killers & vitamin C-(for better wound healing) are prescribed. Hope this information is useful for you. Thanks. Regards.