chemo bad taste

My grandmother was diagnosed with endometrial cancer last year and is going through radiation right now. She finished Chemo. A few weeks later she developed a bad taste in her mouth. She has been going through radiation for about 2 months now and that bad taste is still there. I know it is common to get a bad taste in your mouth during chemo but this has been going on for about 2.5-3 months now. Is that normal? Everything I read online so far said the taste should disapear 1-2 weeks chemo starts. This taste started after the chemo ended and before the radiation. Is there anything she can take or do to get rid of this taste? It is driving her nuts already! She is loosing weight because she does not want to eat because everything taste so bad. We tried using plastic silver wear, chewing gum, hard candy and cold foods, spicy foods, etc. We are at our wits end. Please help!