My grandfather has pancreatic cancer

my grandfather was diagnosed with pancreatic cancer two years ago and now, 2 weeks ago, the chemotherapy treatment was changed to a "better" one. But since May 21, my grandfather hasn't eaten anything substantial, so he is given infusions with all the necessary supplements every day. Also, for a week he has been vomiting continuously and I am very scared. I live in Romania and I have already spoken to some of the best doctors and they say that there is nothing they can do. I searched all over the internet, I even read other people's experiences and I have never seen anyone vomit so much and what worries me the most is the fact that the vomit was the color of mustard and now it is dark brown almost black. And I don't understand why is he vomiting like that when I ask my parents, they don't know either, telling me that the doctors don't know either, and it's not that I don't believe them because I know that he would do everything for my grandfather, but I feel helpless and it's almost impossible I believe that even the doctors don't know what to do with him. If you have ever seen something like this in someone or if you have heard of it, I would ask you to tell me what it is about. I am 17 years old and I feel as if I cannot do nothing but waiting for him to die and that seems horrible to me, only the fact that I say this word in my mind makes me cry. I really don't know what to do, what I could do, also I talk to my grandmother the most who I admire extremely much during this period, I don't think I could be as strong as her in such moments. With my father, I have some reticence because I'm afraid of how he will react when he sees me our own reaction and that's why we reject ourselves quite a lot lately. Life has taken a bad turn lately, it's the first time that the whole family is so bad and I'm not saying that these moments wouldn't come sometime anyway, but it's much too soon, at least I'm not ready and no matter how much I want to accept it, my heart won't let me. When I was little, I guess it was like a "back up" method, that is, to somehow know what to do in a situation like that, I always said that a to die together with my grandfather because I knew that without him I could not continue my normal life, no matter how wrong this sounds. I am very scared of that moment which of course is inevitable because there was a time when my grandfather just fell asleep in the armchair Earlier, I had listened to a story about a neighbor who had also been found breathless in an armchair by his wife. I was in the next room and I kept calling my grandfather and noticed that he did not answer, until I went to check on him my younger sister arrived who was already in the living room and was still calling him, and then a huge fear entered me. When I arrived in the living room I saw my grandfather in a strange position with his eyes closed and I dared to call to him, my grandmother had also arrived and all three of us were shouting at him. Well, that was the moment when my legs went numb, I couldn't feel them at all, so I fell into a coma, my mind was numb and my tears flowed instantly. My grandfather opened his eyes. then, it only turned out that he was deeply asleep, but it was a horrible experience, a rare feeling that I had that was eating me from the inside, my breathing stopping for a few seconds.
So I beg you to tell me anything about my grandfather's symptoms because I feel an inexplicable fear for the near future.