The 20-year-old went straight down the tunnel after being replaced by Malo Gusto in the 65th minute.
Pochettino played down the injury fears, insisting Colwill should be available to face Nottingham Forest on Saturday.
Talking to reporters after the narrow Carabao Cup victory, Pochettino said: “No, he's not injured. It's not a big issue, small problem. He got ice on his ankle but it's not going to be a problem for the weekend.”
The news will also be welcome to England manager Gareth Southgate, who is expected to include Colwill in his squad on Thursday.
Chelsea laboured to victory over League Two minnows Wimbledon on Wednesday night having gone a goal down in the 19th minute to a James Tilley penalty.
Noni Madueke and Enzo Fernandez overturned the deficit but Chelsea were unconvincing over 90 minutes at Stamford Bridge.
Asked about the limp display, Pochettino defended his team. He said: “I think the players we have, we are going to trust in them, with them we won the game.
“I think we are talking very negative, too many Premier League teams are out of the competition and I think we need to talk about the positive things.
“Maybe we should score more, but the game was under control, few actions they maybe should score of course. Surprise me because they are a very good team and the level is League Two but the level is very.
“It does not surprise me because I was here with Tottenham and these type of games are so difficult.”
Chelsea face a difficult third round Carabao Cup draw at home to Brighton in late September, a match Pochettino welcomes.
He said: “If you want to win the competition you should beat all of the teams otherwise it is impossible. For me the same, Brighton we need to play and we play at home and when the moment arrives we will compete with them.”