(not my field - feel free to ignore)
From NHS website -
What if I take too much?
It's very unlikely that taking 1 or 2 extra doses by accident will cause any problems.
But you should check with your doctor if you have taken too much and have any of these symptoms:
flushed skin
feeling sweaty
a fast heartbeat
feeling sleepy
blurred vision
feeling confused or agitated
https://www.nhs.uk/medicines/omeprazole/
Not much on breathing or breath apart from:
"Contact a doctor straight away if:
you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
you're wheezing
you get tightness in the chest or throat
you have trouble breathing or talking
your mouth, face, lips, tongue or throat start swelling
These are warning signs of a serious allergic reaction. A serious allergic reaction is an emergency."