All her symptoms are relatively non-specific. If these symptoms have all recently started I would be suspicious of a viral infection such as with Epstein-Barr virus. If you live in the southwest, valley fever is a definite possibility.
Rheumatologic diseases (such as systemic lupus erythematosis) are possible but less likely.
I would suggest you discuss her symptoms with her pediatrician to get some testing done. Valley fever and EBV can be tested for with a blood test. Screening tests such as a CBC will also be helpful.
Advice and opinions given are based on the information provided and must not be considered an official medical recommendation. The limitations of the internet prevent an appropriate evaluation. Always consult your doctor if there is concern.