"I'm bitterly disappointed," Fenlon told >i>BBC Scotland.
"We'll make changes after that performance, but there's key areas in the team that we need to strengthen.
"You spend days preparing your team and organising and you concede a goal after two or three minutes.
"It gives you a mountain to climb.
"I'm disappointed that they didn't carry out what I asked them to carry out. That's the major disappointment.
"I'm angry. I'm disappointed more than angry. The frustration of not being on the bench doesn't help as well."
"We've released a lot of players since the end of last season and we need to bring players in," added Fenlon. "We're a little bit short.
"If you look at the striker options we had on the bench. We were able to bring on two kids and that's really it.
"You need competition for places within your squad as well."