my westie 6mth pup fell down a large step two weeks ago let out one yelp and wouldny put hind leg down. took her to vet who said there didnt seem to be any thing and to see how she goes. she is still holding this leg up some of the time especially when walking but is quite happy to bounce abount on it and run round like a nutter on it . however i am still not happy. she has full range of movement and doesnt appear to be in pain she even scratches with it .
i am going to take her back to vet tomorrow. should i be worried?

Don't think it sounds too serious if your little dog is 'bouncing around' and the vet can see nothing wrong. Sometimes dogs pull a muscle like we do and it hurts for a few days, I am sure they remember the pain and are also reluctant to use the hurt leg ,a natural reaction to stop the injury getting worse, but when excited they forget and use it as normal. If at all worried go back to the vets and have it checked. Hope your little dog is back to normal soon :-)