My Friend Has Had Prostrate Cancer And A Recent Heart

My friend has had prostrate cancer and a recent heart attack which was tx by 3 stems (stents?) Then had a mental health problem which caused him to be in a state of delusion caused by withdrawal from an overdose of xanax he is 63. Over the past 2 years he has had something that looks like a rash of blisters on his chest and he claims they are getting bigger and bigger. He said sometimes they are itchy. Any idea what this could be? He also has hep C thank you for any help u can give ! Cindy