Can someone explain to me why the difficulty rate went from 3050 to 3456 when the hash rate has not increased???

Difficulty   3,456 TH
Estimated Hashrate    6,236 GH/s

If anything, it has gone down from a hash rate of 6,400.  So why has the difficulty gone up at all???

Coins per day dropped from 32,500 to like 29,500 for what appears no reason.  Can we get an explanation.  Thanks.