It's best not to play rough with the smaller ones, it can cause injury as you've seen first hand. You also should not let him jump off of stuff, it's killer on their tiny joints, easier said than done I know, they like to believe that they are full sized dogs and not little 5lb creatures. I've never heard of them being tied down during neutering before? Who told you that? I'm not saying it's not true, just sounds really odd to me.
I say take him to the vet today and see what they say, it's not like they'll cart him to the back and peform a surgery then and there, but a vet needs to seem him ASAP to make sure that it isn't something that could get progressively worse overtime. If it is LP, like other posters have stated, he may not need surgery at all, just a healthy diet and no more jumping off furniture.
Good luck with your puppy, please if vets recommend surgery don't just not do it because you cant afford it. Give him to a local toy dog or Yorkie rescue so they can place him with someone financially sound enough to provide care for a dog that does require special medical help including surgeries, medication, etc. It is a hard decision, esp. when you've become attached and love your puppy, but sometimes the best thing you can do for them is place them in a different home where they can recieve special care.
Again, he may be okay with just a healthy lifestyle and wont require a surgery at all. But we cannot tell you that over the internet, you need to see a professional to get a professional check and opinion.
I hope all the best.