The Gulls had four put past them by Boreham Wood in a thrilling second half that finished 4-2 - watch match highlights here.
After an opening day stalemate at home to Tranmere Rovers, Torquay were beaten 3-2 at leaders Aldershot Town and then lost 3-0 at Gateshead.
Things didn't get much better in mid-week as Nicholson's side conceded their 10th goal of the season.
"I’m a little bit embarrassed and I feel let down by the players tonight," said the player-manager. "I understand there being a few nerves after what happened on Saturday. You’re not going to win games of football if you give away goals like we’ve given away today. We’ve quite literally given them four, if it wasn’t for Ryan Clarke in goal we would have given them more.
"In the first-half we started well and got on the front foot and then for some reason, because we didn’t score, we went back into our shells and that’s just not acceptable.
"I expect this group, and I’ve said it on Saturday and I’ll say it again now, they will do well. To do well, they have to go out and show it, they have to be men. I’ve brought experience in for that exact reason."
Nicholson added: "I’m going to have a hard job picking the team on Saturday, because other than Clarkey, not many of them particularly deserve to play.
"The rest of it isn’t acceptable. These lads don’t have long to show that they’re the answer. As angry as I am, as frustrated as I am, as embarrassed as I am, I’m telling people and I might probably sound stupid, but this team will be successful.
"They will win games, they will have more highs than lows this season and give it a month and hopefully this night will be a distant memory. They need to start learning, man up and get on with things pretty quickly."
Torquay travel to Guiseley on Saturday.