Splatter marks that won't come off
 

Hey everbody,
First thread and in need of some serious help. Recently bought my first new car, a dark gray 2005 supercrew fx4(looks similar to hivoltagefx4 in the preceding thread). A few weeks ago I took it off-road with a few friends, no problem right? 2 weeks later I washed it and noticed light splatter marks extending from the wheel wells down both sides that won't come out. When I bought the truck it already had very few similar splatter marks. They are inconspicious and only noticeable in certain lights.
I have used a meg's paint cleaner, barr's auto wipe-away, and turtle-wax polishing compound and scratch-remover (in that order). Nothing has worked so far and I'm afraid to use anything more abrasive for fear that I'll botch the paint. My next step is taking it to the dealership or a paint repair. Any suggestions would be greatly appreciated.
Wade

Need pics.