Ok well im 15 about to be 16, And lately like within the past few days i havent been eating as much as normal and the smell of food has been making me feel kinda sick, Also my stomach has been kinda upseat. What would cause this?

Well, if you’re sexually active you could be pregnant.
Typically when you’re pregnant you feel yucky like that.
If you are sure you aren’t pregnant, you could just have the common bug that’s going around. Eat some saltine crackers if you can, they help.
To help your stomach feel better, you can take some pepto or "Little Tummies" it’s a sugary medicine you can buy at CVS that doesn’t taste bad, and it works tremendously.
Hope you feel better soon!