What is this pill -Very small & round, Light green, with N/N on one side and 5 on the other?

There is a pill which almost matches your description - the imprints match exactly but the color is described as blue rather than green. It may or may not be your pill.

Teva-Oxybutynin 5 mg from Canada

Description: Each blue, round, compressed tablet, engraved with N/N on the scored side and 5 on the opposite side, contains oxybutynin chloride 5 mg.

You will find information on oxybutynin at at https://www.drugs.com/oxybutynin.html