My two month old kitten has an infection in his leg and a high fever, what do I do?

I am from Bangladesh, and we don't have any good vets in our country. About two months ago, my cat gave birth to four kittens. When they caught fever I took them to a vet. He gave them injections which made their legs limp. But it cured the fever. I took them to the vet again to cure their legs. This time he gave them an injection which instantly killed two of the kittens. And the injections did nothing to cure their legs. Now I am really afraid to take my kittens to the vet. And one of them has an infection in his disabled leg, which was caused by dragging it around too much. He also has a high fever and his heart is beating too fast. I don't know what to do. And I don't think the vets would be of any help.