But the Pompey skipper believes he can now look forward with optimism after putting his latest ‘freak’ issue to bed.
Robertson returned from four months on the sidelines with a 45-minute outing in the Papa John’s Trophy exit at Cambridge United.
It represents a significant landmark for the 28-year-old, after suffering an unusual and unfortunate hip injury picked up in training.
After suffering from a stress fracture to his foot and other unrelated issues at Rotherham before joining the Blues last summer, Robertson told how he was left wondering why the football gods seemed to be against him.
But now Robertson believes those problems are finally in the past.
He said: ‘I felt I had a good start to the season after having a few injuries the previous season.
‘It was a freak injury in training and it was so frustrating, mentally more than anything really after everything I’d been through over the past couple of years.
‘It’s natural to doubt yourself when you go through something like that, but because I had been through it before I knew what to expect with the rehab mentally.
‘It does affect you at first knowing you are going to be on the sidelines for months.
‘You are in the training ground every day with the physios and can’t get out on the pitches.
‘It’s even more frustrating because it’s not been a recurring injury.
‘I could probably accept it more in a way if it was recurring injury.
‘It was quite a rare injury and I don’t think the surgeon had seen many cases himself really.
‘I do seem to pick up some freak injuries and I questioned myself because of that. Why does it always happen to me?
‘I’m just glad it’s in the past now and I’m looking forward.’
Robertson explained how it’s been the mental as much as physical challenges, which has proved the toughest obstacles to overcome in his time out.
The Scot underwent surgery in September and was finally able to accelerate his return at the end of last month, before his competitive comeback at the Abbey Stadium.
Robertson added: ‘It’s been mentally tough for me. I’m just glad, touch wood, it’s over.
‘When it first happened, I didn’t think it was that bad.
‘But when I went for the scan and got told I was going to be out for three or four months, I was devastated.
‘I’m just glad those four months in the past now and I’m looking to the future.’