Rotherham manager Steve Evans claimed referee Roger East made a "foul and abusive comment" towards one of his players on Saturday.
Striker Dwight Gayle and midfielder Luke Howell scored a brace apiece, with Medy Elito also on target for Dagenham & Redbridge as they romped to a 5-0 win.
Evans was furious with his team's display but also drew attention to East afterwards.
He said: "The player came to the bench and told me what had been said. To say I was surprised is an understatement and we addressed it with an official at half-time but I am not going to let that detract from what went on on the pitch."
On the performance he added: "It was a shambles from start to finish. We switched off for the opening goal and from thereon in it was our goalkeeper, Andy Warrington, versus Dagenham.
"If we're being honest, Warrington prevented us from conceding more and I don't think we created a real opportunity in 95 minutes. It was totally unacceptable - the worst performance I've had as a manager."