Welcome to HCM
We understand your concerns
I went through your problem description. I suggest you not to worry and you could walk it over and ignore it for the time being. Again if the pool is not deep more than 15 feet. Pressure difference plays the trick. But the difference should affect your eardrum
as well. But pressure difference is negligeable upto around 15 feet.
After that cleaning stint, you are stressed and tired, therefore the breathing difficulty. Do you think there was algae inside the pool? If so get checked by a physician for any algae particles in the air passage.
Hope this clears your doubts. Available for further clarifications.