It is possible still, while doing the ball joint, was the rest of the suspension checked?

Things like control arm bushings and tie rods?

Tie rods are good, I don't know if my dad checked anything else.

I just find this strange that all this happened after the new tires were put on, so I'm really putting my money on off balanced wheels.

If I can find someone around my place with a set of jack stands, I'd move around the wheels to see if that'* the issue.