There's no other explanation. Shorts are losing big bucks on ROYL and they need to cover cheaper. Their standard tactic is to use whatever fire power they have to sell some shares at the end of the day to scare longs into selling the next day. Hold firm and let them pay the piper!
The MMs could be among the biggest shorts in the stock. So they would have an interest in bringing it down. ROYL is still on the naked short list, BTW. There's pressure on the shorts to cover soon, and they want a good price.