Wanderers boss Ian Evatt says Declan John was taken off at half-time against Stockport County due to chest pains.
Liam Gordon played the second half as Ian Evatt’s men were held to a 2-2 draw against the Hatters in the FA Cup first round proper.
Eoin Doyle and Elias Kachunga were on target for the Whites, who are due to play the replay at Edgeley Park next week.
Evatt also revealed John had suffered from a non-Covid related illness earlier in the week.
“He had one or two chest pains, we don’t know what that is. He’s had a bit of illness in the week,” said the Bolton boss.
“Obviously there’s not really Covid issues, but there’s quite a lot of heavy colds flying around and chesty coughs and he’s had one of those.
“He was struggling a bit to breathe.”
It is a blow for John, who recently returned from a spell on the sidelines due to a groin injury.
Wanderers are back in action on Friday night when they welcome struggling Crewe Alexandra to the UniBol (KO 8pm).