The former England centre-half was clipped by Leroy Fer and looked in agony after rolling his ankle in the final minute.
Terry had a difficult afternoon at the back as the Swans came from behind to lead 2-1 in the second half, only to be pegged back in the final 10 minutes by Diego Costa who scored a brace in South Wales.
Blues boss Antonio Conte confirmed his captain had an injury after the match, but added that he wasn't 'worried' by the problem.
However, Terry posted images of him getting a scan and a heavily bandaged left ankle with angry faces on it later in the evening, and a short video of "some late night work trying to get the swelling down".
“I don’t know the extent (of the injury)," Conte said.
"Tomorrow we’ll see the situation about his ankle. He is a warrior. I’m not worried.”