HIYA !!! Glad you are all done and hopefully recuperating x
I should think if it's totally flat the fizzy stuff would be fine. Always phone them and check no matter how insignificant you think a problem is though, as we're not experts x
Get some wind relief in ready in case you need it now though as that wind pain is horrible sometimes. I used deflatine and gripe water and found them useful. Plus gently toddle about now and then if you can and of course the usual sip sip sip the liquids!
Speedy recovery x