Can Separated From Friend Cause On And Off Fever And Cold In Kids?

Yes please, my nine year daughter has been unwell on and off since the beginning of January. This started off with tiredness, followed by sickness and a temperature. She had real lethargy and tummy pain and was sent off for blood tests (reassuringly clear) and urine tests. White blood cells appeared in urine sample but the results have come back clear also. A rash did appear for a few days but was checked out. She has a temperature on and off, has bouts of energy but is then tired and weepy. Has had mild diarrohea plus coughs, colds etc. She still complains of sore tummy and is weepy. Have talked to teacher to check all is ok at school, and it appears to be. Her best friend left her school a year ago and she misses her, could this be a contributing factor - going back to doc next week and probably going to see paediatrician - any ideas?