What Causes Fatigue,nausea,headaches And Body Aches?

My daughter is 14 has been experiencing fatigue, nausea, headaches, body aches and states that every once in awhile she feels a numbness and tingling sensation throughout her whole body and then feels like she is going to faint, and gets nausea and cold sweats. She was diagnosed with mono back in November but seems to continue with alot of these symptoms. She is very active in sports but her symptoms are really starting to affect her school attendance. Any suggestions?