down about 50% on my daily XVG earnings too...
Again, this is because the difficulty has gone up because more people mine verge. If your hashrate stays the same, earnings will drop.
But you can't just blame difficulty on this. Even if you go whattomine, it will say you should be getting 37 xvg coins dual-mining with eth @ 12.1 Gh/s hashrate, but in reality I'd be lucky to get 30 coins a day. It is usually 24-26 xvg a day which is about 35% less of what i should be getting.