I have a open wound under my gum it's a kinda white reddish look n had pus coming out of it?

Pus: in the mouth is concerning for infection that needs treatment by a physician or dentist.

Question ?: What is it? Most likely a draining abscess. What should you do? See a dentist for treatment. And if you're taking antibiotics as your topic tags state, don't bother... it's not going to solve your problem, but in actuality prolong the inevitable: dental care. Feel better soon...