Hi, My Dad Had A Bare Metal Stent Put In

Hi, my Dad had a bare metal stent put in after a heart attach back in 2009. Soon after that, he developed a rash which has become more serious. These red rashes are all over his face and body. He has been to several dermatologists who are saying it is Psoriasis, but nothing works to clear it up. Then his cardiologist thought maybe he was allergic to Coreg so we stopped that also. It seems to be getting worse, so I took him to a allergist who thinks he may be allergic to his stent ???????????? What do you think ? thank you