I've had a bad flu (negative COVID test but possibly a false negative) in September, and one morning when I woke up and felt difficulty breathing I ended up riding an ambulance to a hospital. (Ambulances are and doctors doing home visits are widely available and free where I live).
Turns out, it was a psychological thing; something similar to a panic attack, with my lungs completely clear. They gave me anxiety medication and the feeling has gone completely. Not saying that it's necessarily the same with you, but if you experience hyperventilation and feel like you can't breathe, try to relax and breathe slowly and deeply. May be it's not as scary as it seems.
Turns out, it was a psychological thing; something similar to a panic attack, with my lungs completely clear. They gave me anxiety medication and the feeling has gone completely. Not saying that it's necessarily the same with you, but if you experience hyperventilation and feel like you can't breathe, try to relax and breathe slowly and deeply. May be it's not as scary as it seems.