Need help fixing a leaking PVC pipe joint?

I just replaced a leaking PVC joint and now my replacement is leaking! I cemented this in perfectly, but apparently there is a pinhole leak somewhere. The real problem is that I have no more pipe to attatch to if I cut the elbow off that I cemented in. Any thoughts on how I can just plug the pinhole leak? Silcone, plumbers putty? Cement another piece of PVC over it? Help!