What does my dog have and what is a natural way to cure it

For constipation or possible colic I reccomend a single piece of childrens ex-lax but make sure it is NOT the chocolate kind. There are fruit varieties or even a pill. You could, instead, use fiber powder such as metamucil with warm water over the dog's food. Other suggestions include mineral oil or cod-liver oil. Again you really SHOULD NOT administer these items unless you know for sure that consipation or colic is the problem which you can really only know for certain from a vet visit. If your dog is not constipated these things will cause diarreah which will lead to further discomfort because if his legs already hurt think how painful it must be to squat in the potty position not to mention dehydration and a flushing of the vitamins your dog needs to fight off a possible infection.

For anything else, there are no home remedies. Dogs aren't like people, they can't tell you they have a tummy ache from eating to many cookies and take a spoonfull of pepto to feel better. Vets are there for a reason and it's one thing to not be big on doctors for yourself when you're sick but putting a dog in pain and doing nothing to ACCURATELY help him is just plain mean.

If you can't take him to a vet because you can't afford one then I suggest you take him to a vet and tell them you can't afford it. Many vets care enough for the dog to do what they can to help him despite your lack of funding, even if it means putting him down to put him out of his misery. I haven't even covered the possibilities of spinal-damage.