Food aversion with immunotherapy

Hello! I am seeking help for my husband. A year ago, he had a malignant melanoma tumor removed from his right foot. He did 8 treatments of Keytruda but then had a saddle PE in August and we stopped the treatments. However, 2-3 weeks before the embolism, he started having an aversion to food, especially meat. He said all meat smells rotten and he would get a slick metallic taste in his mouth. He vomits anything that strikes him as off. This began in July and he has now lost over 60 lbs. I read a post on here from 2017 where a woman described her husband's food aversion and it matched what we are seeing.
My questions: Has anyone else dealt with this AND how was it resolved? Our primary doctor has prescribed Dronabinal (synthetic weed) to try to stimulate his appetite and suppress his vomiting. We have only just started it although he did say yesterday that he felt the first twinge of hunger he has had in months.

Sweets taste fine to him. He currently lives on Ensure, anything sweet or with cinnamon, Cream of Wheat (which I sweeten and put vanilla in) and fruit. He used to eat carrots but recently turned off of them and other vegetables.
Thank you!