Could you expand on which type of bottled water (filtered, spring, de-ionized, distilled, etc.)? First thing would do is to transfer you ill frog to it's own hospital enclosure where you can monitor feeding and observe if it's pooping, etc. Will wait for your answer on water type because that could be part of problem. Also, a water change every 2 weeks is not enough, even on a tank with a filter. After you tell us water type, will recommend a cleaning schedule.

IRT supplements, think 3-4 times a month is a light schedule. Did person who recommended that gave you reasons for it? Thank you !