My poodle is limping

Question
I have a year and a half old black miniature poodle. She is  in perfect shape according to our vet. She has been limping for months and we have taken her to the vet about it several times. Every time he examines her he finds nothing wrong and just decides to put her on prednizone. As soon as she is done she starts limping again. He does not want to X-ray because when he examines her and does all the leg movements he says that nothing is loose or out of place and she seems to not be in any pain, apparently ruling out patellar luxation. I am wondering if this could be bulging discs in her neck or something akin to that. If not do you have any ideas?  

Answer
Has she been checked for LCP disease and hip dysplasia?  Miniature poodles can get both these disease.  They are both a type of joint malformation in the hips.  Your vet DOES need to do an X-ray to see this.  So if your vet that you are going to now wont do it then find another one that will.  There is obviously a problem that needs to be looked at and if your vet isnt finding it I would find another vet or even look up a specialist.