What is causing my hair to be greasy right after washing it

As soon as I wash my hair let it dry naturally it greasy I wash it every other day dont use conditioner as it makes my hair more greasier looking i let it dry naturally I've brought many shampoos but still my hair looks greasy I brought a shampoo the other day for build up OGX apple cider vinger shampoo but after I used it the other day my hair still looked greasy after I let it dry I'm at my wits end with it now nothing works I give up. Can someone recommend something or at least know the cause I've had enough..