My aunt is mentally disabled and recently lost her appetite.............?

Ok I have been taking care of my mentally disabled 57 year old aunt for about 6 months. About 2 months ago she got bronchitis really bad and it took a while for her to get rid of it. Since the illness she has not had any appetite. I also have had to puree any food in order for her to eat. Just so you all know she will be going to the doctors this Wednesday for a check up. But I think her doctor is kind of odd. we are looking for a diff rent doctor but until then we have to see him. Anyways I guess what Im trying to get at is why would she have a sudden loss of appetite? I hope and pray its not cancer. Although all her blood work came out fine when I took her to the ER. Well wait they did say her white blood count was a lil elevated but it was due to the infection. I really want someone to answer this who has dealt with people who have went through this. I know that 57 is not elderly but I think it is for her due to her mental condition. People always told my grandmother that my aunt has lived for a long time considering her mental disability. All I know is that I am doing the best that I know how and I don't want to send her to a convalescent hospital. I just took her out of a group home because people warned me that it wasn't a good home anymore. Please help with any suggestions. What could I give her so she can gain some weight? Thanks.