12 year old, puking, nauseated , loss of appetite , no fever, tested negative to strep, also has accasional headache, also a sore throat what could this be?

Viral illness: This could be one of a number of viral illnesses. The number one that comes to mind at your child's age is mono. A blood test could be done to rule this in or out. Many of these viruses that cause a similar constellation of symptoms are self-limiting - this means your body will clear them up on its own, and child should get plenty of rest, fluids and good diet. Get her further checked out.