Jones' final years were plagued by injury before he retired last season.
He wrote in a column for BBC Sport: "Unfortunately there were times when I was at United when I did not look for help. My coping mechanism when I had any problems was to stay silent, and that was probably my downfall.
"I didn't open up to anyone, and I would hide my injuries from other players and the staff. I put a shield up so no-one knew what was going on, apart from my close family.
"I only spoke about this for the first time on a podcast last week, but one of my lowest moments was when I was trying to play through the pain of my knee injury, when it had got to a point where the doctor had to inject my knee before every game I played so I didn't feel it.
"I was on the bench for a game at Brighton but one of our centre-halves was struggling in the warm-up, so I thought I would be pro-active and get the injection before kick-off.
"It was embarrassing for me because I didn't want anyone to see that I was struggling, or in pain - I was meant to be a tough guy as a defender, remember - so I went into a cubicle in the changing room just as the manager started his pre-match talk, and got the doc to inject me in there."