Back acne, Red spots, hairfall, dandruff

I have acne all over my back. Also I get red spots anywhere on my body every alter day and sometimes it also causes intense itching while some looks like acne ...it stays for a few days and then go bt leaves marks. After sometime I get this red spot somewhere else. I also have extreme hairfall and dandruff. Previously I have consulted many doctors and took medicines. These hairfall dandruff and back acne reduces till I take medicine but once medicines is over these again come back and never cured actually. Earlier after getting a blood test it was reported that I had less vitamin D around 8.0 and I was given medicines for 3 months. I don't know it's relevant or not but I still mentioned. Kindly please guide me what is the problem exactly and how can it be treated?