Extreme wrist and knee pain?

ok im only 13 but i just got a hip surgery for a slid growthplate, which is something that only happens during the growth plate, but now during recovery, being in a wheel chair has made my bones weak and in serious pain. ive been drinking 4-5 large glasses of milk along with a full pinapple every two or 3 days. I also use braces for almost all my limbs witch works very well, there are ones at the 99 cent store that work the same as the expensive ones, and i frequently ice my hurting limbs and take ice baths. This workes for me and my bone/ joint pain. ( this happens for no reson and i am not obeise, i only weigh 101 pounds)