Should I be worry if my sister has fatty acid oxidation disorder or no? Pls read need answers she’s only 10 going to be 11?

My sister bella was born with a rare case of cystic fibrosis which doctors said will not effect her just maybe with allergies from time to time. Now when my sister was around 7 she got a bad virus besides my other sister but my sister bella had it the worst because she couldn’t stop throwing up for many hours, they checked her cystic fibrosis and they said it wasn’t coming from that.. now it’s  been 3 years or more and from time to time she has to go to the hospital because she starts throwing up to the point where she can’t stop and she starts throwing up blood. Besides this she has her episodes of being nauseous and it comes time to time or can stay for months then subside only for her to get it again but then start throwing up and now when she gets a simple cold it brings it on. Doctors now think she has cyclic vomiting and now tonight I reading about fatty acid oxidation disorder, what is that? Is that something I should have her tested for? She’s been tested for many things and looked out so I’m just wondering because her doctor thinks it’s due to her stress and needs medication for her to relax and make her brain and stomach work together to not have these episodes. My sister has only been delevping a chest and he’s kinda hormonal I just want to know should I be worried for fatty acid oxidation disorder or is this just from stress and I shouldn’t worry about that?