I'm a 20 year old female. i'm an otherwise healthy vegan, sugar and gluten free. but suddenly i have low grade fever, upset stomach and no appetite ??

Probable virus: My best guess is that you have gotten a viral infection. A virus like this will likely only last a few days at most. If not hungry it is OK to not eat for a couple days but stay well-hydrated. Consider chopping some carrots, potatoes, greens & garlic and simmering for at least 20 min. to make a mineral-rich vegetable broth to drink.