McPharlin felt some discomfort in his calf during the second quarter of the Dockers' two-point loss to Geelong on Saturday night and had to be substituted out of the match in the third quarter.
Speaking on The Sunday Footy Show, the Dockers veteran did not rule out the possibility of being sidelined for the next two to three weeks.
"I don't presume what it's going to be," he said.
"These things, who knows what shows up in a scan.
"But to not play out the game wasn't a positive sign, so we'll see what the result is and move forward from there."
His latest injury battle adds to the quad, knee and previous calf issues that have restricted him to just 13 games this season.
Despite his latest setback, the 32-year-old doesn't fear his season might be over.
"I've had a few injury issues this season and that's been a bit disappointing personally, but certainly the team's in really good shape and I really want to be a part of it," he said.
The 237-game veteran is out of contract at the end of the season, but has not ruled out playing on in 2015.
"I find it very difficult to make those decisions in season," he said.
"In the clear light of day at the end of the season I'll sum up everything and make a decision from there.
"Early parts of the year I was playing some really good football – some of probably the best football of my career.
"I'm not ruling out the possibility of playing on next year but, again, that decision will be made at the right time."
Twitter: @TravKing_AFL
