Hi hun,
there is a Growth Spurt around 3 mos, do you think he's had that? Or could be having it now?
Otherwise, can we see your daytime routine? How is he doing with the formula during the day? is there a possibility that he's having problems with it? The windiness and grunty crying sounds like he's uncomfortable. :-/
As for being smiley when the light comes on, well, I suppose that's just distraction!