Unless you clearly hear the noise from the right crank area don't count on it being the right side. Sometimes the release of pressure on the left crank can cause a click. Do both pedals and ideally try a different pair if the click persists. You said you "checked" the screws/nuts (actually either a bolt or nut) but does that mean you saw they were not loose or that you tightened them? Another common cause on the right is the chainwheel bolts.