Tetracycline has been used as home treatment for cases of Red Leg according to what I read. Unsure if successful or if same dosage as for fish or different concentration. If I had aquatic frog with known bacterial infection, would treat first with combo of Melafix and Pimafix as per bottle instructions. Add Melafix in morning and Pimafix in evening daily for one week and then re-evaluate frog. If at any time frog shows discomfort do a water change and discontinue treatment. Be aware Pimafix will wipe out any white worms in filter media and substrate which could lead to increased ammonia or nitrites.

If after a week frog shows improvement continue daily treatment for a total of 10-14 days. If no improvement; then maybe your frog's bloated condition is caused by parasites (flagellates or lungworms). Good luck !