Doncaster Rovers have confirmed that defender David Mulligan was admitted to hospital on Wednesday evening.
The New Zealander fell ill during Wednesday and was taken to Doncaster Royal Infirmary during the day before being released, but after further examination from the club doctor, he was re-admitted.
The club have not commented on the illness but say he is in a stable condition and now recovering at home.
Meanwhile, fellow defender Stephen Roberts has spoken of his delight at agreeing a contract extension at the club.
The Welshman has played 20 times since moving from Wrexham in the summer and will now stay at Belle Vue for at least a further two years.
"I am really enjoying my football here and it's great that the club have seen fit to offer me a new deal," the 26-year-old told stellargroup.co.uk.
"We still have an outside chance of a play-off spot so we are all fully focused on that.
"There is a great spirit at the club and it is a good place to be playing football at the moment."