After a cagey affair it took a slice of luck to ensure Paul Ince's men maintained their 100 per cent Sky Bet Championship record.
The Tykes have now lost two in two in the league following an opening-day mauling at home to Wigan but were vastly improved with striker Chris O'Grady twice going close either side of the break.
Flitcroft said: "If Chris O'Grady goes and sticks that chance away just after half-time then it could have been such a different game," he said.
"As we worked hard we're all gutted. It was looking like whoever scored the first goal would go on to win but to lose it like that is sickening really.
"Up until that late stage in the game we had defended so well. We'd had to withstand throw-ins, corners, free-kicks, everything, but we'd defended heroically.
"It's a difficult one to swallow.
"We created a few chances but we've not been as slick or nearly as clinical this season yet.
"That's something we'll be working hard on, on Monday morning.
"It's been a horrible way to lose but I was always surprised at how direct Blackpool were.
"That's been the most direct I've seen them in a long while.
"We've had chances to counter-attack of course but once one goes in like that right at the death then you're never going to get it back.
"We need to bring in one, maybe two strikers. It's been no secret we've been trying to do that but despite some frenzied work behind the scenes nothing is happening just yet."