6mth olds are still going to be sloppy walkers/movers/ etc. I wouldn't worry about it until you get those xrays done..He's still growing.
You may want to work on building up good muscle tone by swimming which is low impact..
I had one gsd who never jumped on anything, his hips were fine, it was just the way he was.
Danger Danger vom Kleinen Hain aka Masi
"Angel" Jakoda's Bewitchen Sami CD OA OAJ OAC NGC OJC RS-O GS-N JS-O TT HIC CGC
"Angel" Steinwald's Four x Four CGC HIC TT
"Angel" Harmonyhill's Hy Jynx NA NAJ NAC NJC RS-N JS-N HIC
"Angel" Jakoda's Jagged Edge