Shooting pains fron Ankle to Knee

My Son a 10 year old healthy kid was playing on the play ground Thur.  On the monkey bars he slipped & hit his shin, fell forward while his leg was stuck in the bars.  He was ok at first & was able to walk but it hurt.   End of the day he was not able to walk on it.  Friday morning swollen in ankle and toes, so I took him to Doctor for an X ray.  They thought there was a spot on the Xray by the ankle that did not look right & sent him to Ortho.   Ortho Doctor says he though there was a fracture in the growth plate.  While putting the cast on he started crying that his knee hurt. Doctor came back in & He decided to also use a knee brace. When he tried to stand up the pain was very bad.  So they ordered a wheelchair.  Home he had a pretty good night. Sat morning he stated having shooting pains in his knee.  Called ortho & they told me to take him to the ER.  At the ER they cut the cast off & did more Xrays & an MRI.  They said they thought that there was also a fracture in the growth plate in the knee.  Ortho came in & said no fracture at all.  We were transferred to a childrens hospital because they could not control the pain.  PS they gave him many drugs in the ER & he was still screaming. When we got to the other hospital they were concerned about the amount of drugs in his little system.
They had ortho doctors look at him & all his Xrays, MRI the only thing they said was there was a small sport that looked different on the ankle but should not be causing this much pain.  They were thinking that the pain was muscle spasms.  So the admitted him  and Sunday morning did an ultra sound which looked good.  Ortho doctor decided to do a bone Scan Monday that was negative.  They started him on Neurontin and Flexeril to control the pain on Sunday which seems to be helping some.  Monday night and our first night at home, he has screamed in pain for about an hour saying that the pain is shooting from his ankle to his knee, with the most pain in his ankle.