Ive developed a skin rash that started on my inner thighs and then spread to my shoulders, ankles, buttocks, and the sides of my stomach. It started off red, but now its turned black, and there are little bumps that appear when its itchy. What could this be, and how should I treat it?

It sounds like you may be experiencing a fungal skin infection, such as tinea corporis (ringworm). I recommend using an antifungal cream like Clotrimazole 1% cream. Apply a thin layer to the affected areas twice a day for 2-4 weeks. Additionally, you can take an oral antihistamine like Cetirizine 10mg once daily to help with the itching. Make sure to keep the affected areas clean and dry, and avoid sharing towels or clothing to prevent spreading the infection.