Jewell thought his side's first-half performance in the midweek third round replay success at Sheffield Wednesday was dire but their pitiful display against Alan Irvine's side on Saturday left the former Wigan manager livid.
He blasted: "Whatever team we put out we make basic, fundamental errors, and when you concede goals like we do you're not going to win matches.
"I think that what happens is as soon as one thing goes against us we haven't got the character and confidence to bounce back from a mistake.
"Every time we make one mistake it leads to another. It has been happening all season and that was embarrassing - it is the only word I can use
"I would like to think it can't get any worse but I said that after Tuesday. We don't seem to take anything that comes to us and don't put teams under pressure.
"We work hard all week, look good in training, but we come to Saturday and seem to duck it as a group. That is why we have got seven points and have just been knocked out of the FA Cup by a Championship team."