Lens for concert photography

Hey, i recently acquired a gx85 and am looking for a good small lens for concert photography. I have the 12-32 kit, and a 25mm 1.7 already. Size is a factor because some security/venues will not let you in with something massive. At the same time I might need some zoom depending where im at and low light capability. Any recommendations, or anyone have experience shooting concerts and have advice? Thanks