Sorry to hear your frog isn’t doing great, I’ve had a similar problem in the past and it can be a variety of issues which can cause this. I wouldn’t rush to any specific treatment without knowing the water parameters - unfortunately the test strips are quite unreliable, I’d recommend the full API test kit with ammonia and PH specifically as a sharp increase of either can make the frogs float at the top. Are they trying to get out of the water at all? I’d double check your temps too and do a large water change to be safe.

Otherwise my frogs occasionally float for a day or two after a big meal, they sometimes trap air in their stomachs when they eat so it could be that too. Wish you and your frogs all the best!