Random back leg issues

I have an 11 year old boy cat named Julian. He's usually a happy, healthy, indoor-only kitty. About six days ago, I noticed he hadn't moved at all from his spot on the bed. Around 8pm, I realized he literally hadn't gotten up to eat, drink, or go to the litter box. I was really concerned and went in to check on him. He was alert, and I gave him some treats and he ate them just fine, so I decided to wait until morning. The next day, he was acting like nothing ever happened - up and about and his regular self. Then, two days later, I noticed again he wasn't moving from his spot, and I decided to pick him up. He yowled a little bit, but seemed overly lethargic. I put him on his feet, and he walked about three feet - very, very gingerly and slowly - before laying down again. I called the vet and the earliest they can see me is tomorrow afternoon so that's when we're going (unless he gets worse.) 

My question is this: is it ok to wait a day? He has trouble getting up, and walks like it really hurts him, but he's eating and drinking the stuff I bring to him, and goes to the bathroom when I take him to his box. When he's not sleeping, he seems like himself - just unable to move and a little extra grumpy. His gums and tongue are pink and his nose is wet. Is he in an emergency situation or should it be ok to just take him for his appointment? I have the feeling I will be getting next to no sleep tonight as I worry and fuss. :/

Is he limping at all?

How are his back legs?

Is he peeing normally?

If he's going to the bathroom normally, peeing normal amounts, then I would guess it could be arthritis.

If he is not peeing normally you may have a urinary issue going on.

He's not really limping, but he is unable to go from a laying o a standing position on his own, and he doesn't walk more than a few feet. Does arthritis come on suddenly? Because I haven't noticed him having issues before. He does not want me anywhere near his back legs, so i am pretty sure they're hurting him or at least one is. He pees a normal amount, but I have to physically pick him up and put him in his box, wait for him to go, then lift him out because he is unable to get in and out on his own. He hasn't gone outside of the box, though. 

Hello, sorry for the scare you are going through. It happens that we had a very similar event this past week. And this is the shirt version.

Our cat Bruce is a male, about 2 years old, and a little over weight. I had noticed a slight limp, and after checking for obvious injuries, we found nothing. I put it up to some play fighting/running/jumping injury, like a human might get. Then, suddenly he was nowhere to be found, not in his normal places, and we went searching for him. To our horror, we found him all the way upstairs, where the litter boxes are, laying in his own secretions. When we tried to call him, he began dragging his hind legs. Scary stuff.

We called our vet and informed him of the situation. I thought the worst, believing that he had either a severe spine/pelvis fracture and was paralyzed. After telling our doctor all the things we observed, he diagnosed a soft tissue injury, since I couldn't find any moving bones through palpation. (I am also a EMT). I wanted to take him straight to the emergency room for x-rays and full labs. Our doc suggested we first isolate him in a room with no stairs to climb, or other obstacles, and keep him from other cats so he wouldn't play or fight. He also told us to give him meloxicam.

Once he was on the pain meds, and in a place where he didn't have to climb stairs to eat or use the bathroom, he began to improve immediately. Not sure if our doctor is that good, or just lucky, but the pain meds, combined with a less stressful environment has made him much better. The isolation room is also our bedroom. At first he was unable to climb/jump in bed, so I had to pick him up. Now he won't let us sleep unless he comes into the bed of his own, and splits us.

I hope that you have a similar experience, and as horrifying as it may seem, it could be just a simple strain/sprain or even a pulled muscle. I do recommend seeing a vet though, and getting a thorough check-up just to be safe. But don't panic, I hope it is something simple. Sincerely, the kittykeepers.

I forgot to add, give him a pan that he can enter without too much issue, it will be messy, but causing him undue pain should be avoided, no stairs either.

Thank you so much for the info. We went to the vet today and the official diagnosis is intervertebral disc disease, which I guess can happen in longer cats (he's very long.) Looking at x-rays, it looks like two of his vertebrae in about the middle of his back have almost no space between them - they almost look like one big vertebra. He was prescribed Prednisone and Torbugesic and we will do another check-in next Friday. He has been sequestered in our bedroom for the last three days, with food, water, and litter box all at ground level, but we don't have an easy step-in box yet. Time to go shopping.