As others have said mostly sound like CO2 build up from shallow breathing. You can learn to recognise the symptoms before it become a problem and a couple of deep breaths will clear it if caught early. It starts as a minor need to breath that you are likely supressing as you are already concentrating on breathing it is similar to a minor need for salt and water you feel before heading on you way to dehydration. My other past time is playing assorted wind instruments so can easily recognise the start of CO2 build. I can breath in and breath out a lot of air quickly so I was really concertrating on my breathing for my first few dives to avoid the popping up issue I found the hardest thing was making sure I took deep enough breathes to avoid the CO2 issue. Just make sure you listen to your body because it can tell you something is wrong before you are throwing up on the surface.
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