My lad does the same thing pretty much!!! He is 8 months old, I have to use a harness otherwise i'm too worried he will get loose of his collar and when in a mad stage,will get run over or just do a runner!!! He is a weird one though,as one minuite we can be walking ok (bit of pulling) then all of a sudden he also gets that look in his eye lol and goes nuts,swinging himself round and round on the lead jumping at me,it is a nightmare(you can see people thinking weird things lol) The only thing I have found that stops him is by carrying a water bottle and when he starts jumping,I give him a drink,sometimes it works but other times he will then change his attention to the water bottle and refuse to walk. It is a hard one I know,but very reasuring to see others are in the same boat,good luck.
Seb & Casper