What Causes Appetite Loss, Fever, Chills, Diarrhea, Shaky After Diagnosed With Melanoma?

My 80 year old father was diagnosed with melanoma on arm between his wrist and his elbow. He had surgery to remove the cancerous melanoma Feb 2013 and went through a series of radiation treatments. He has been taking, since October 2013, 150 mg tafinlar twice daily plus one 2mg Mekinist. He was doing very well until the last two weeks. He started experiencing fever and chills, loss of apetite, and in the last week he has experienced severe night sweats, occasional diaherrea and has began to exhibit shaking in his arms that looks like parkinsons and walks somewhat unsteady. Other medications he is taking is for high blood pressure. His blood pressure the last two weeks has been low... around 120/62 with a pulse of 122 to 126.