Why are my dreams so horrific?

please help,i had a dream and it was about i was in a hospital but it wasnt for me,i was just there walking around looking at all the patients it was wierd,then i switched into a little girls room she was colouring and talking to me(it was nightime btw)and she said she was dying of cancer then she went into a cardiac arrest, Then wierdly i switched in this peaceful garden with the hospital behind me and it was like a big posh white palace,it looked hot and i can see flowers and birds whisteling then the most horrible thing i saw,my mom whom im very close to in real life, was bieng wheeled out in a wheelchair by my nan! and i ran up to find my mom and no offense or anything this is what happened in my dream,my mom was suddenly disabled like she had suffered brain damage.in real life she is perfectly fine for now. why did i have a dream like this i also had another one which i couldnt fit in so can someone please help me with my other dream too?