Dog acts like his leg is hurting then a few minuets later he is fine and jumping up and down.

What breed is he? What's his age? How long has this been going on? When is he most favoring his leg?

Sorry for the questions, but I need more info before I can offer a guess as to what's going on.

I'll be the Devil's advocate here. After a few "minuets" (sic) minutes? he probably loosens up! LOL

If it looks like his leg is hurting - it is. If he then seems ok, it stopped hurting. Sounds like intermittent nerve pain, just like I have all day and night, LOL.
Pinched nerve, arthritis pressing on a nerve - two common reasons.
You can't really expect anyone to provide a good answer based on what you describe.