He jumps like he's drunk.. What gives?

My Diesel is at least 6 years old.. Though we've never been able to truly guess his age, because he's just very small - He weighs less than a gallon of milk, but isn't thin. He's got stubby little legs, and he's got little polydactyl thumbs on his front paws.

In the last week or so, he's been missing jumps he can normally manage. He has to claw his way up about two or three kitty-strides in order to get on the sofa. It's been hit or miss, though - Sometimes he'll make it, other times he'll fall catastrophically to the ground.

Any advice guys? Thanks in advance!!

is he walking like his legs aren't doing what he wants them too? basically, like you said, he's drunk? if so get him to the vet ASAP, actually I would anyway, these can be signs or toxoplasmosis or even FIP

My vet told me that is a classic sign that something is wrong with a cat...when they start missing jumps that they usually make with such ease. As suggested I would get him to the vet and get him checked out. Hope it's nothing serious.