What Causes Loss Of Appetite?

My husband was in the emergency room on Wednesday for pain in his kidneys, fever and chills. He was diagnosed four weeks prior with an infection in his prostate and placed on an antibiotic. The hospital discharged my husband on Wednesday saying that the only thing that they could find was an abnormality in the levels of his Liver. They placed him on another antibiotic to treat a bacterial infection. The new medication was giving him digestive problems, where he constantly felt full. A nurse from our primary doctor s office told him to go off the medication and have his blood taken again on Monday to see if the levels for his liver have improved. For several days now, my husband has been extremely lethargic, has a lack of appetite and this morning had a white colored stool. He called the oncall service who said that he should come in to see them next week. I am extremely worried about my husband and am wondering if I should just take him back to the emergency room. What are your thoughts? Thanks, Jocelyn