The 27-year-old claims he is now about 95 percent back from his battle with Guillain-Barre Syndrome, which is a very rare and serious condition that affects the nerves.
The autoimmune disorder mainly affects the feet, hands and limbs, causing problems such as numbness, weakness and in extreme circumstances even paralysis.
In an interview with WFAA sports, Frederick revealed the astonishing details of his battle with the disorder.
“I was probably less than a week out, from not being able to walk anymore,” he said.
“Best case is you get some of that sensory stuff and maybe your calves or feet aren’t working quite as strong.
“And worst case it begins to attack your diaphragm and stops your body from being able to bleed.”
Fortunately for the Dallas Cowboys’ center his diagnosis was not the worst-case scenario, but it also wasn’t the best case.
The 6’4” offensive lineman had previously played 16 games every season, after he joined the Cowboys in 2013, but missed the entire campaign last year due to his fight with the disease.
Frederick revealed he had difficulties doing tasks most people take for granted.
“It was also hard for me to get upstairs,” he said.
“And the kids both stays upstairs.
“It got the point where I couldn’t even carry them and put them to bed.
“My son is going to be three here at the end of February and my daughter is going to be one here in March.”
Frederick hopes it will only be one to two more months before he can rejoin his Dallas team-mates.
He claims he’s now about 90 to 95 percent back and is still looking to regain some more strength and explosiveness.
Frederick is a fan favourite in Dallas and the four-time Pro Bowler was missed by the Cowboys last season.
Dallas made a poor start to their campaign going 3-5, before turning things around and winning the NFC East on 10-6.
They defeated the Seattle Seahawks 24-22 in the Wild Card round, before losing to the Los Angeles Rams 30-22 in the Divisional round.