Square taper crankset develops play after changing bottom bracket
As some commenters have indicated, your crank arms are worn out.

We can speculate all day about what was the cause, but since you indicated that you felt some wobbling, that means they are now because that is the fast-track to ruining the square taper interface.

You'll have to replace your crank arms.* When replacing them, make certain that your crank bolt is tightened to spec. It needs to be pretty dang tight. Also, when you get the new crank, replace the crank bolts with the snazzy allen headed crank bolts. 

*If you are short on cash or like to gamble, you could also just replace the crank bolts with the snazzy ones, then tighten the absolute snot out of the bolts. While a low chance of success, it might work. The BB spindle is hardened steel, and the cranks are aluminum, so you don't pose much risk to the BB spindle if you choose this option. But still abide by the no riding when the crank is wobbling rule.