Why is my swollen, red, yellowish finger so painful?

Sometimes not having enough vitamin D3 can cause people to lose their hair. You should keep taking the vitamin D supplement as the doctor told you. You should try to eat more foods that have iron and protein in them as well. One thing that might help is finding ways to relax when you are stressed. 

Acanthosis Nigricans is what you are suffering from, a skin condition that causes your neck to darken compared to the rest of your body. This may occur if you are obese or have diabetes. It is important to work on reducing your weight and controlling your blood sugar levels. A balanced diet, regular exercise, and maintaining the cleanliness of your skin can gradually improve this problem. 

It seems as if you may be suffering from severe hair loss. It may as well have been caused by many factors like stress, hormonal changes or a disease. I would suggest visiting a dermatologist, who could examine your scalp and diagnose the reason for hair loss. They can then develop a customized treatment plan for you

It seems like your skin is not glowing and lacks moisture. These issues may be due to other reasons such as lack of proper hydration, non-use of sunscreen, or dry location. One of the best things to do in this respect is to ensure that your skin takes in enough water, use a good moisturizer that is not too harsh, and eat a healthy diet by including fruits and vegetables. Use sunblock when outdoors to keep your skin protected from the sun. These actions may improve your skin and consequently, you may have radiant skin.

Itchy and red rashes are some of the common signs of sensitivity when your skin's non-acceptance is projected. This might be due to the presence of certain chemicals in the spray to which your skin is sensitive. Perhaps, you should try a gentle body lotion to reduce the itching and rashes.