What Causes Nausea, Loss Of Appetite And Loose Stools?

I am a 25 yr old female and for 5 days now I have woken with nausea, light headedness, loss of appetite and loose stools. My period ended on the 27th of April and I havent been sexually active since before then so i am not pregnant. I also took an at home pregnancy test and it was negative, i am also on the implant. I can't figure it out. I just walk around trying not to be sick, getting chills and trying to take deep breaths. I try to eat and it feels like it just sits below my chest and i have to drink alot of water to make it go down. If i dont, i vomit. Please help, i don't know what to do.