My son, Ryan who was is 9 has complained about the exact same thing since he was about 1 year old.  Before he could even speak he would grab his knees and cry for extended periods of times.  I discussed it many times with both our pedi and our endo.  But to be honest no one seemed to ever take it seriously and at times would say it was growing pains.  This has never really set well with me but his labs have always been pretty good, only changing his dosage twice in his life, and his bone age is also with in 8 months of his age.  We saw his endo on 4/14 and I’m awaiting his test results from that.  We had his magnesium and calcium checked to see if they could be the culprit.  I’m hopeful to hear from her soon as they usually take about 3 weeks to come back.  I told her that at 9 my son is very capable of telling me how he feels and that he is frustrated because "he feels his own doctors don’t take him seriously".  I think she actually felt bad when I told her that.  I think it made her take it more seriously.  It broke my heart because hearing him say that made me realize that they bother him more than I even thought.  I am constantly rubbing his legs and it can even be first thing in the morning.  It just doesn’t seem to matter time of day like with growing pains.  Growing pains typically hit when tired or in the evening.  Ryan has always been fairly active with sports and is constantly outside whenever he can be but my gut feeling is that it’s not from being overworked or growing pains.  Both my husband and I found it so interesting to see this thread this evening.