I am sorry about your dog's illness. But have to tell you that we are not veterinarians or experts here, but only people who have had some experience of dogs, or their own dogs, and have some common sense, and wish to try to help others and their dogs with suggestions and advice.
I think the only, and best thing you can do for your dog is to find a vet anywhere near your home, who will be able to give some treatment. The drugs that Margot has just mentioned (Benznidazole and Diminazene Accturate) might be the best hope for your dog, if you can find a vet or any medical professional to administer them.
I really hope your dog will be okay....
I am sorry your dog is so ill.
I am not familiar with this condition so had to look it up and it sounds like it can be a serious infection and show the signs you are describing. I read it can also affect the heart and prognosis is not good.
Is this a disease that is common in your area? You are in India? I read it is more common in Central and South America.
I saw two drugs that are used, Benznidazole and Diminazene Accturate by injection for 5 days. Maybe that is what you mean? Was the heart checked by x-Ray or ultrasound?
I am sorry I cannot be of more help.
The Vet in your area would be your best source for treatment.
I hope your dog will get better.