Bottom bracket mysteriously squeaking
Never just tighten one side if a bracket if it isn't tight enough yet. Always do this:


Untighten the lockring which is not fixed to the bracket (mostly left side).
Tighten the bracket inside the frame very, very tight, while the lockring sits at its place very loosely.
Tighten the lockring again.


It sounds like you may have tightened the lockring, while the bracket wasn't tight enough in the frame yet.

Also, let someone hold the bicycle. In this way, you can push your tool tightly in the lockring while using force on the tool.

And mind that the pedals on the cranck need grease, the crancks on the bracket needs grease, and the bracket inside the frame also need grease. Any of these parts can start to squek if no grease is used.