There was a time when I believed Plaquenil wasn't helping me either and I stopped taking it. Big mistake! About six months later, I was dragging patootie and couldn't figure out why. My rheumy suggested I resume the Plaquenil, which I've done, and noticed an improvement after a couple of months.
Remember that it takes a while to see the effects of Plaquenil and if you aren't consistent in taking it, it'll take even longer.