About 4 or 5 days ago i noticed that there was a whiring sound (sorry hard to explin via text) that i concluded was the auto. the sound started out to be faint and would go away after driving for about 10m. But the sound got worse, louder and took longer to go away. Once it got to its loudest it started to become intermittent, i could drive home from work and it would be there nearly the entire way home from startup, but then the next time i drove it wouldnt make any noise at all. regardless of hot or cold start.

Today i changed the fluid to transmax z, as recommened here, and it seemed to help.
When i moved the car before changing the fluid, no noise.
When i moved the car after changing the fluid, full noise, no change.
I then went for a drive and it was heaps quiter but still there, i then let the car sit for 20 mins and went for a drive again, the noise was still there but very faint and could notice the auto was nicer.

But when i went for a drive just then, about 4 hours after last drive, the noise is still there and it is the same as it was before i started.

I am planning to change the oil again next weekend as i didnt drain the torque converter so there is still bad oil in there.

My question is, will doing another change in about 200km help or should i just take it straight to an auto shop?