How do i know if i have necrotizing fasciitis?

This is a very : Serious infection. While i feel you would know if you had it, any hint at it, such as early cellulitis with ulceration of skin, a feeling of air bubbles or crackling under your skin where you think the infection is, systemic signs like fever and chills as well, or, as it can be seen, a large dead area of skin down to muscle. If you even think you may have it, get to a hospital.