The Kilcher Homestead is a 600 acre Pioneer Homestead that has been protected for perpetuity via a ConservatIon Easement. The Kilcher Family has also preserved the Historic Cabin and site as a LIving Museum.
Yes, negative pH is possible, but not in water as a solvent. The range of pH in water is 0 to 14 (to be more precise, it is -1.7 to 15.7, but for simplicity's sake, we start with the usual values.) Thus, what pH indicates is the ability of the acid to form H3O+, which can then donate a proton.
Purchase an at-home pH test. If you suspect you may have a vaginal yeast infection, the most common type of yeast infection, and you have had one in the past, then you can take a pH test and self-diagnose at home. Normal vaginal pH is around 4, which is slightly acidic. Follow any instructions accompanying the test.