What Causes Nausea, Vomiting, Diarrhea And Inability To Retain Food?

Hi.My mother in law has been on Dialysis for 10yrs.She has started to feel nausea, vomiting, and having diarrhea. she hardly eats because sometimes when she does she just throws it all up.Is there any type of food that I can try to give her that is easy on her stomach And is drinking tea bad for her,she really enjoys that.