A son asked his dad to “come quick” moments before collapsing at Meadowhall Shopping Centre because of what proved to be a fatal pulmonary embolism.
An inquest into Mark Bennett's death heard how staff at Boots performed CPR in a bid to keep him alive during a 50-minute wait for paramedics to arrive.
Mark had developed venous thromboembolism after a fall which left him with an injured foot.
Sheffield's Medico-Legal Centre heard on Tuesday that parents Steven and Elaine Bennett had to watch in agony as first-aiders battled to keep their son alive.
IT worker Mark, 38, had fallen at a London Underground station 10 days before visiting Meadowhall for a day out on April 14 last year.
Yorkshire Live reported that as his parents waited outside Boots, Mark called dad Steven from inside, saying: "Dad, come quick, I feel funny".
Giving evidence at the inquest, Steven said: "I couldn't see him and the next thing I knew he was in one of the aisles - he had already collapsed.
“He had staff all around him and they were giving him CPR, the staff were tremendous. Boots staff phoned for a paramedic straight away but were told it could be half an hour.
"I shook my head in disbelief at that point but they actually took 50 minutes. I always wonder if they had turned up earlier whether they could have saved his life."
Coroner Stephen Eccleston heard how on April 4 Mark tripped on some steps at a London Tube station and landed “awkwardly”, injuring his right foot.
A&E doctor Akash Mittal, who treated Mark at London's Royal Free Hospital in the early hours of the following day, told the inquest Mark's foot showed signs of a fracture and tissue damage and had an air cast boot fitted to the foot.
Crucially, it was decided that Mark posed no risk of developing deep vein thrombosis and so blood-thinning drugs were not prescribed.
While Mark was recovering at his parents' home in Grimsby, he complained of pain at the back of his leg and attended Grimsby's Diana, Princess of Wales Hospital.
However, an orthopedics doctor diagnosed 'minor swelling' and recommended a further assessment three weeks later.
The inquest was told that during his assessment at hospital in London Mark was scored as posing 'zero' risk of developing venous thromboembolism when measured against a scale known as the Plymouth VTE Risk Score.
However Dr Akash Mittal admitted that since news of Mark's death emerged, he had changed his practice, 're-emphasising' the risks that injuries such as Mark's posed.
Speaking outside of the inquest, Mark's family described how he was “in the prime of his life” when he died.
The 38-year-old was “really excited” about buying a flat in Manchester, while his IT career specialising in Apple and Microsoft products was “going somewhere”.
Describing the events of April 14, Steven said: "It was awful, they're just images you can't get out of your mind.
“It was a harrowing 50 minutes and we still have our moments. There's nothing worse than losing one of your own kids.
"It seems the scoring system the hospital has got is totally flawed - why didn't they give him blood-thinning medication as a precaution?"
The inquest continues.
