Luke Donald has left hospital in Georgia after being admitted with chest pains on Friday.
The former world No 1 withdrew before the first round of the RSM Classic in Sea Island after feeling ill.
Donald underwent seven hours of tests at a local hospital before returning home where his post was filmed."Scary 24 hours, had some chest pain and was admitted to the ER.
"Turns out I had a wicked case of flu. There'd been a stomach flu going through our household a few days ago and it got into my GI tract and oesophagus and it was presenting itself like heart issues.
"Feeling a lot better today and really appreciate all the support and messages I got.
"Really sorry to have had to withdraw from the RSM Classic but better safe than sorry I guess.
"Appreciate the support again, see you out on the links soon."