The on-loan man struck from the spot to open the scoring but the Gills' Rory Donnelly equalised later in the second half before Brandon Ormonde-Ottewill was given his marching orders.
Luke Williams made three changes to the matchday squad at the Priestfield Stadium. Darnell Furlong and John Goddard were both handed starting berths while Yaser Kasim, Luke Norris and Jordan Young all missed out. There was a place among the substitutes for second-year scholar, Scott Twine.
With John Goddard leading the line flanked by Brad Barry and James Brophy, it was the hosts who carved out the first half-chance of the contest as Cody McDonald’s overhead kick inside the box was blocked and was easily gathered by Lawrence Vigouroux.
After some early pressure from the hosts, Town fashioned an opportunity of their own when Goddard drifted in off the right flank and skewed a shot across the face of goal and wide.
Goddard would have an even better chance as the clock ticked towards half-time – set free by a clever reverse pass from James Brophy, the former Woking man saw his shot take a nick off Stuart Nelson before the ball was hacked off the line by Max Ehmer en route to goal.
Emmanuel Osadebe drilled a shot over the crossbar from distance for the hosts while seeing his close-range flick tipped over smartly by Vigouroux.
Just before the break, Michael Doughty’s teasing cross evaded everyone in the box before the midfielder whistled a shot high over the crossbar.
Town made a bright start to the second half, with Brandon Ormonde-Ottewill fizzed a cross towards Brad Barry but the full-back couldn’t convert under pressure from the defender.
Ten minutes after the re-start, Darnell Furlong scampered into the box and was clipped by Paul Konchesky. Michael Doughty took charge from the resultant spot kick, striding confidently up to the ball and burying it into the bottom corner to give Town the lead.
Substitute, Jordan Stewart then teed up Brad Barry but the full-back's shot was blocked over the crossbar.
The visitors' lead lasted just over 15 minutes before the Gills drew level through a substitute of their own. Rory Donnelly swept home a cross from the right to equalise.
Swindon had chances to win the game late on by James Brophy fired across goal and wide before Furlong's shot was spilled by Nelson.
In the dying minutes, Brandon Ormonde-Ottewill was shown a red card after being booked for the second time.