If your trusted mechanic suggests ball joints I'd suspect that too---the speed you bumped into something shouldn't affect any suspension part unless its already on its way out......

With your mileage its entirely possible one or more ball joints could be worn sufficiently for replacement, especially if they're OEM---no grease fittings. If you go the replacement route I'd do all four and maybe check/change the various front end bushings. I did my '00 E250 along with tie rod ends and drag link and used urethane on the radius arms and axle pivots too. Every other oil change I grease all points---good habit to develop.

Anyway best of luck-----hope its nothing more than a BJ or two!