Pls don't dock Pongo's tail. That is not the solution and he will be very distressed by the loss of his tail.
I actually posted a response to your problem some time ago but it never appeared. I don't know what happened to it. I think Pongo's problem may be malessesia or yeast infection.
Pongo has a weak immune system which is why he is susceptible allergies that cause his skin to flare up with malessesia. Keep his hair as sort as possible because anything that gets caught up in it is irritating and once he starts to scratch, only makes it worse. Ask your vet for some antihistamines to break the itching cycle to help his system calm down.
Changing vets constantly is not a good idea. Pongo's skin problems can only be resolved by a process of elimination. Different vets have different ideas - as you have seen yourself - and different approaches towards the same goal - Pongo without skin problems. They will go through the process in a different order too. When you change vets the info already in the vet's notes is lost and wasted because the whole process of note taking has to start again.
Rice is fine for your dog. Allergy to white rice is very rare that is why it's babies' first food. Other foods you can try feeding your dog are boiled potatoes, sweet potatoes and pumpkin. They are known to be low allergy foods.
Many dogs have allergies to chicken - it's not the chicken but the farming methods, the antibiotics and hormones. Kampung chicken should therefore be ok.
Good dog foods are Natural Balance (the one with duck) and Eagle Pro (sardine and salmon). I used to feed my dogs Blackwoods (Catfish formula) but that has an ingredient, vit K3, which is artificial, serves no known purpose and may be toxic in the long term. Please go to the link and take a look at it for info - it is very interesting.
http://www.dogfoodproject.com/index....badingredients.
Some people feed their dogs raw food but I don't because I don't like the look of it and used to feel sick when I fed it to my dogs. I feed my dogs dog food supplemented with steamed vegetables (carrots and cabbage) with some garlic (anti-tick and -fleas) and steamed fish (deboned patin). Two of my dogs have skin problems that flare up from time to time and this is a low allergy diet that works for them.
I also give them plain yoghurt. It is good for their digestive system. When dogs take too many medications - like antibiotics, especially - the bacteria in their digestive systems get destroyed. It can cause yeast that occurs naturally on the skin to grow out of control - it is already a delicate balancing act for a healthy immune system so one that is weak would find it even more difficult.
Finally, when you bathe Pongo, make sure you dry his hair thoroughly with a hair dryer - yeast thrives on damp skin. Letting him run in the sun is not enough - you have to dry his hair with a hair dryer.
Hope this helps.