The former Leeds Rhinos and Great Britain scrum-half, 46, is fit again and helping train the squad as they prepare for Saturday’s crucial Super League game at play-off rivals Hull KR.
However, it was only recently that he was off work and unable to get out of bed for a fortnight due to the effects of contracting Covid in late July.
That was particularly alarming for the Dewsbury-born Sheridan given his younger brother Brendan – the Oldham assistant coach – spent two weeks in an induced coma in intensive care with the virus last year.
“I was in bed for two weeks solid; I couldn’t get out of it,” recalled the long-serving Tigers No2.
“I had all sorts of symptoms and it got to the stage where I did think if this gets any worse it will be hospital time.
“Fortunately, it didn’t get to that. The scary thing for me was that my brother had it and he came within hours of dying.
“That’s what was in the back of my mind; I was really conscious of that. It was difficult. There was nothing you could do. It’s just time that hopefully you do heal and you do get better. It’s been a long, drawn out process and the last week or so is the first time I’ve felt all right. I’m just grateful really.”
His brother, just 41 at the time, had been the first Covid patient to be put on a ventilator at Pinderfields Hospital in Wakefield after he fell ill last April.
Asked what advice he gave, Sheridan said: “Hang in there!
“It was a difficult situation he was in and obviously at the back of his mind he was thinking about what he went through and was just hopeful I didn’t.
“So he was supportive and tried to keep me in good spirits.”
Thankfully, Sheridan has been back out on the training pitch in recent weeks and is now looking to plot a victory which will confirm Castleford’s top-six spot.
They are in the sixth and final play-off place with just two regular rounds remaining but Rovers will usurp them if they prosper at Hull College Craven Park.
Sheridan conceded they are “very unlikely” to have Man of Steel Paul McShane available but half-backs Gareth O’Brien and Danny Richardson are fit.
England hooker McShane left St James’ Park with a protective boot on his foot after coming off in Saturday’s Magic Weekend win over Salford Red Devils. Sheridan said: “Macca’s got an ankle injury He’s unlikely for this week. We’ll have a look on Friday but he’s very unlikely to play at Hull KR.”
Castleford fielded centres Peter Mata’utia and Jordan Turner as makeshift half-backs against Salford and they performed admirably.
Sheridan said: “We’ve got players who can fill in to do a good job but to have two specialists back is really good. Danny Rich’ is in contention and Gaz O’Brien so that’s a bonus for us.
“It’s a massive boost as it’s a key game. It’s great we have them for a must-win game for both teams.”