I'm just gonna say it.
Nunu needs some serious help. His winrate right now sits at 45% and isn't going to rise anytime soon. You'd be better off playing Ivern right now with him building Redemption/Locket every game and being a godlike teamfighter.
The only people who play Nunu are Nunu mains that play him maxing his E instead of his Q which is what you generally would be maxing but isn't worth it when junglers right now are needed for doing high damage when ganking. Plus counter jungling isn't really worth it with how snowbally this Season has been so far,