Jewell told BBC Radio Suffolk he was unwilling to predict how long the Irishman would be absent.
"It's a blow for the player and a blow for us, I don't really like putting timescales on stuff but certainly he won't be involved Saturday," he said.
"He had a scan Wednesday and there's a centimetre tear in his stomach muscle."
Healy found opportunities few and far between under previous boss Roy Keane, but has missed just one game since Jewell took over in January.
Meanwhile captain David Norris is still a doubt for Saturday's visit of Portsmouth.
The midfielder, 30, took a knock to his knee and ankle in the 1-1 draw with Barnsley a fortnight ago.
"He trained with the physio Thursday morning," added Jewell.
"He did some straight line running, twisting and turning, and we'll see how he is Friday morning."
Source: BBC Sport
Source: BBC Sport