leaking bathtub on second floor

Hi all, new member here looking for guidance/input please.

I'm useless at DIY, so please be gentle. Bought out house new 8 years ago. Previously had water come thorough in the same spot 2 yeartsago, it was repaired under warantee by the builder. I seem to recall that 'something' (drain plug???) was not installed correctly

Noticed that water was coming through the ceiling directly underneath the bathtub this morning, the day after I gave my young son a bath last night. I unscrewed the drain, and did not notice anything unusual, mind you there was very little to see.

All of the caulking around the tub and on the floor seems good, so I'm looking at the the plumbing connections as the guilty party.

Suggestions?

Hoping not to have to open up the adjoining wall to the bathtub or ceiling below.

Your help is appreciated, thanks

If the leak occurered while someone was taking a bath, I would check the overflow to maker sure that the rubber washer is centered to the opening and tight. Sometimes when a bath is full, and the overflow is not tight and centered you can have a leak.

A good test would be to fill the tub below the overflow and let it set to determine if the lower drain is holding.
Then fill it until water is going into the overflow to check that location.