acid reflux----using omeprazole, but wake up in middle of night coughing and gasping for air

Your dose isn't sufficient. It can take a while to get the right dose. 

You also have to watch what you eat and when, so eating a big meal just before you go to bed is a no no. 

Raise the head of your bed by about 6 inches, this will help keep the acid down. Adding extra pillows won't work, you have to raise the bed so try using some bricks or books.

For your throat try some exercises to relax your vocal cords which are probably reacting to the acid and closing. Take a big sniff in through your nose and then purse your lips like whistling and softly blow out breaking it into about three out breaths. So big sniff in and blow,blow,blow. Practice this ready for when you wake up.

Google vocal cord dysfunction exercises and you will find more. It might not be this but this is what i have because of silent reflux it is thought.

 

Try and cut out tomatoes, onions, garlic, chillies, any fruit apart from melon or banana, mint, chocolate, juice and coffee for a couple of weeks at least.

And no food within 3 hours of bed time. 

Gaviscon Advance helps a lot of people lst thing before bed.It forms a barrier on the top of your stomach so the acid is harder to escape.