Why is my hashrate so low?

I understand that RVN has a lower hashrate than most, but mine has gone down a lot. I used to pull 10 RVN a day from my single RX-580, at about 11 megahash. Now I'm barely pulling 10, and it's more around 8 or 9 megahash than not. I haven't changed anything. It's the exact same PC I've always used. Why has my profits decreased, and how do I fix that? I also mine ETC and my profitability has also gone down by about 8 percent, so I'm very confused. Any help would be appreciated