Quick update...

Per my morning test, pH rose to 7.7 today. However, the temp also rose to ~8, so I was able to swim in the pool and spent about 5 hours in or around the pool with no eye irritation at all. Clearly it was the high pH causing me issues. Thanks again for the help on that.

We have an appointment with my son's allergist tomorrow, so if I find out anything interesting regarding Borax / borate allergies, I'll update here.