Cancer and Psoriasis

Had P for 60 years. Plaque on legs mainly. Spring 2015 plaque disappeared within a couple of weeks replaced with a rash type over my upper body. Dreadful. Itching 24/7. Limited sleep, stressed and tired. Diagnosed with cancer Oct that year and treated with chemo until April 2016 .Marvellous stuff; all my historic aches and pains gone mainly because the chemo had Prednisilone [steroid] incorporated. Then [Oct] I started sweating, itching, skin dreadfully dry and P came out to play with a rash over my torso. Note torso not legs. Cancer Dr's no idea what is causing the problem as blood tests and PET scans show everything OK. Derm specialist doesn't know or, more likely, doesn't care. Fobbed off with the usual tube of useless cream instead of finding out what causes the sweating. ANY ONE HAVE A SIMILAR EXPERIENCE ? - desperate situation, but my hair will fall out again if I have chemo !!