Brief Answer:
She is likely suffering from anorexia nervosa

Detailed Answer:
Hello,

Thanks for posting on XXXXXXX

I am so sorry for your mother's condition which apparently has lead to a serious complication. Upon reading your post, there is one condition that popped into my mind and that is anorexia nervosa. Anorexia nervosa is an eating disorder that makes patients lose more weight than is considered healthy for their age and height. It is more of a psychosocial problem rather than a physical disorder. Therefore, your mother must be evaluated for major depressive disorder as that might be the major risk factor involved.
If depression or psychiatric disorder is not the origin of this loss of appetite your mother is experiencing then, other physical consider should be investigated (even though it should normally be ruled out first) but since I am assuming that after seeing her doctor who seemingly did not find any problems, this makes me think only of psychosocial problem which might require antidepressants medications to relief her and hence get her to start eating. Also vitamin, mineral (e.g zinc supplement) and appetizers supplements should be included in her medications to help with this disorder. Suffering from taste disorder or dysgeusia could be as a result of taking certain medications.
Her age should also be considered a major risk factor for her problem as she might just be refusing food for no apparent reason and gives an excuse of bad food taste so no one can ask her why she is refusing to eat.
I believe you need to take her to a psychiatrist for further evaluation.

Hope this helps and wish you the best.
Dr. Nsah

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