First of all, sorry for my bad grammar, I'll do my best to explain my problem the best I can.
I have a small dog that's about 2 years old. He is of a mixed breed and weighs about 16 lbs. I don't know if it matters, but here's a picture of him:
Yesterday at about 10PM, he tried to jump on a couch, but missed it. This happened before and just like in all previous occurrences, there were no signs of him hurting himself. But somehow this time something was wrong.
When he landed on the ground, he instantly screamed in pain a little bit. I helped him getting on the couch and he screamed in pain again. He started shaking, especially in his rear legs. He looked really scared and didn't react to my calls. He started to avoid me as if I did something wrong to him. It's not him. He's the most hyperactive and playful dog I ever had and he never misses a chance to play. Another thing that happened is he started holding his tail down between his legs which is another thing he never does.
Before this occurrence, he has no problem jumping up and down from the bed 100 of times per day and he only had two speeds. He was either sleeping, or running around like a rocket.
Right now, the morning after, his tail is still between his legs. He still has his apetite, he occasionally runs for a few yards, but it's clear something is wrong with him because he isn't playful at all and he rests all the time. He also doesn't jump on his rear legs like he did hundreds of times per day and he doesn't jump onto the bed / couch any more (I help him with that).
I can touch him anywhere on his back without getting a negative reaction. I can massage his rear legs, move his tail, and I don't get any negative reaction.
The only negative reaction I got today was when he was on his back and I massaged his legs, and he suddenly screamed in pain for a moment. It looks like he has some kind of cramps and he isn't relaxed at all.
I know I need to take him to the vet, but I live in a remote place and the chance for me getting him to the vet will be in a few days from now and I don't know what to do until then.