Frequently have rashes and black heads on my back neck and chest?

Could be acne.. Acne can take different forms, especially on the back and chest. There are some great creams that can help, and even some oral antibiotics may be appropriate. To help in the meantime, try to avoid synthetic fiber shirts, always shower immediately after working out and sweating and avoid scented or perfumed soaps. But talk with your doc if it's not improving. Hope this helps!