The incident happened as the team faced Flyde Ladies FC at the Hetton Colliery Welfare, Welfare Road, on Sunday.
The game was halted for around an hour.
Courtney said she believes the reason for the collapse may be down to potentially having diabetes.
Most Popular
-
1
National Mackem Day 2022: 14 things you'll only understand if you're from Sunderland
-
2
Met Office announces yellow weather warning for thunderstorms across North East following heatwave
-
3
Durham police appeal for help to find 33-year-old in connection with alleged burglaries
-
4
Banned and uninsured Sunderland driver given jail warning by judge
-
5
Campaigners rally against Local Plan after farmland in Cleadon earmarked for 156 homes
She took to Twitter to thank fans for their support during her recovery.
She said: "Not the most ideal situation to be in after the first match of the season, but it's better news than expected.
"I potentially have diabetes, which was the reasoning for the collapsing and convulsions on the pitch.
"Also, I'd like to apologise to all the travelling fans for the extension on the game - I hope that wasn't an inconvenience to anyone and I am sorry if so.
"But, thanks to all of you for the messages and I know I'll be back in no time."
A North East Ambulance spokesman said: "The event was managed by St John's Ambulance who called us with a request for transport.
"We sent an ambulance and arrived at 2.45pm and took a teenage girl to Sunderland Royal Hospital."
A St John Ambulance spokesman said: ‘We can confirm that our team of first aiders attended an incident at the Sunderland AFC match and that the patient was transported to hospital."
Sunderland AFC Ladies Tweeted: "Thank you for your kind messages about Courtney Stewart after yesterday’s game.
"She was taken to hospital as a precautionary measure and is now home and feeling much better."
The Echo contacted Sunderland AFC for comment.