Is white spot on son's hand vitiligo?

Not taking proper food for so long can damage your body severely. The symptoms you talked about, for instance, your constant feeling cold and desire for hot water all the time, could indicate you are suffering from something serious such as malnutrition or damaged organs. You are supposed to go to specialists for diagnosed tests and treatments. You have to understand that it's not too late to get good treatment and work towards being healthy.

I can see that scratching you due to a street dog can be a worrying issue for you. From your information, the scratch is not too deep, which may mean there is a low chance of infection. Watch out for any redness, swelling, or warmth around the area. First of all, wash the scratch using soap and water and then apply the antiseptic cream to the area to avoid any further infection. Watch the scratch for a few days, and if you spot any of the infection signs that are getting worse, like more pain, redness, or pus formation, it is better to go to a doctor. 

These dark spots are known as hyperpigmentation administered after skin injury therapy. This is a natural condition that occurs after any injury to the skin, such as a cut or a scrape. Azelaic Acid is a very suitable solution, but, likely, you will not see impressive outcomes soon. Vitamin C serum and products with niacinamide are also good for you. Always remember to protect your skin from the sun with sunscreen. 

Ringworm is a cutaneous infection which a fungus causes. Symptoms such as red, itchy, and scaly spots that look like circles may occur on the skin. The ringworm can be transmitted through contact with infected people, pets, or objects like shared towels. Therapy involves antifungal creams or tablets. You can also prevent the spreading of the infection by keeping the area clean and dry.

Keloid scars are marks that are raised and dark because of the excessive collagen. These scars can be highly annoying for people. Utilization of silicone gel or sheets will assist in the flattening and bleaching of the scars. Besides, the application of bio-oil can be even more effective in enhancing the look. Hence, the most important thing is the time and patience to stick to the treatment to be able to see the effects of it.