Calf pain in 9 year old boy

[sassysas]

My lad has had severe calf pain for 10 months since a much heavier friend of his jumped on him play fighting.  His symptoms for 10 months include.
1. Waking in the night always once but sometimes 3/4 times. When he wakes nowadays he up for one hour taking a hot bath to relieve the pain.
2. He has a protrusion around his leg kidney , a large hard protrusion .
3. He has recently complained of kidney pain as well as calf muscle pain.
4. His left leg is much smaller than his right . Several centimeters difference in size.
5. He hardly ever puts weight on the left leg - he walks with a limp.
6. His left leg is colder than the right and has a lesser blood pressure.
7. He suffers pain on and off all day long , bouts of anything from 5 minutes to 2 hours at a time.
8. Pain killers do not take the pain away.
He has seen , 11 doctors / specialists  , had an MRI scan and xrays but they do not show any bone damage . The doctors and specialists do not know why he is getting this calf pain and what the protrusion around his kidney could signify .  Three of the specialists are pediatrician's.  Is there anyone reading this who has heard of or known any kid with symptons similar to my childs ?  We are desperate for help in solving his ongoing pain. Any sensible suggests welcome.