Okay, so this is an important clue. Do you know if the bottled water at your workplace is sourced and/or processed locally? If both your town's water source and the five-gallon containers' source had some change in processing (eg hypothetically they decided to add a step or a substance during purification) it might be affecting you. They usually disclose these types of things in a newsletter that comes with your water bill, but call your town's water utility and see if they've made any changes.
Okay, so this is an important clue. Do you know if the bottled water at your workplace is sourced and/or processed locally? If both your town's water source and the five-gallon containers' source had some change in processing (eg hypothetically they decided to add a step or a substance during purification) it might be affecting you. They usually disclose these types of things in a newsletter that comes with your water bill, but call your town's water utility and see if they've made any changes.
Here's a link to the EPA's public notification rule that may be worthwhile to read.
https://www.epa.gov/dwreginfo/public-notification-rule