Is she evidently having any trouble breathing?
My Gds had it badly twice, 1st time at 4 months, he was in ICU for a week both times, but a perfectly healthy 6 yr old now. First sign was always that breathing was evidently rather more of an effort than normal.
I’d def. take her back to A&E if at all worried.
FWIW they usually grow out of it by around 2 - Gds did. It’s when their lungs are so tiny that it evidently affects them.
Might add that the first time he was in ICU - sedated and tube fed - there was a tiny little 3 week old in the next cot, who’d been premature anyway - she recovered very well too. Gds - who by 4 months was a roly-poly porker - looked enormous beside that very wee one.
Needless to say, we were all profoundly grateful for the excellent care he received.