Malecite

I have a 3 year old Pembroke Corgi and since yesterday morning he has suddenly started limping.
I noticed it is his right rear leg, he tries not to put any weight on it, and if he runs or tries to jump he colapses as if he cant support himself on it.

I have massaged, stretched, rubbed and everything, he doesnt mind or seem to feel any pain anywhere.

Does any one have any advice ?
I am not completely sure how this may have happend.
The only thing i can think of is that he jumped of the couch in a wrong way.
He usually jumps from the couch and bed all the time, so i dont know if it could have caused it.

Do you think he just got a small injury that will heal in a week, or could he have broken something ?
Again, he doesnt seem to feel any pain, he tries not to use his leg at all, and if he puts too much weight on it when he does use it, he collapses.
Any help is appreciated.

I dont have very much $ to be bringing him to the doctor but will if you think this may be serious.

thanks in advance