I searched for a solution but couldn't find anything on this. When nanopool made the payout it showed in etherscan.io:
Type STANDARD ADDRESS Balance 0.0000 ether 0 Wei $0.00 HardFork Balance 0.0503 ether
The transaction still doesn't show in myetherwallet.
Solved with the help of a friend. I didn't realize that MyEtherWallet basically assigns addresses, but isn't actually a wallet to store in. I think that's why so many others seem to have this same problem.
I downloaded Jaxx, chose the coins I wanted to trade and imported my MyEtherWallet address and then made the transfer.