Skin rashesh coloration from red to blak

I have random rashesh on my skin from past 2 months approximately at first i thought it might be a normal allergic situation but now there are so many spots all over my body in different areas like thighs forearm palms foot ankle beneath the foot belly button etc..at first these were pink spots and then it got itchy and then they are started to turning into brownish black in colour it is hot on the spot of rash when i feel like scratching it and then it cools down...i am also facing cough and nausia plus back pain since these rashesh started increasing...i feel dizzyness and decreased appetite even though i love my meals but it is really getting hard to eat them as i start to feel like vomit just by seeing any kind of food these problems are increasing since i got those rashesh...they are spreading everywhere on my body.