tank you all i really happy to see your odds to help me, my puppy wight is great he had the surgery 2.5 months ago, i also think maybe it some infection, he is popping normal, he had x ray last time but we didnt succed to lay him on his back, i thing his food not realted to his condition,i think maybe his loung not so good, its what the vet also meantion" i saw better one" like he said, tommrew i will go again to the vet to hear his opinion i will take video of him after short run and if he wont help me understand my boy, i will go to someone ealse and for sure i will update you all!! tanks again i feel we are like family here its the best feeling i can get!