I cycle in and out of tenderness too.
No pattern, but the growth has slowed.
In about 18 months I have gone from normal under bust of 44 to a 49 to 50 bust .
No discernible reason, doctors are baffled and we are still hunting for a diagnosis beyond’ idiopathic’.
I think many gynecomastia people have tenderness, not that I know many beyond this forum.