Did you have a pretty long trip to the campground or have you been primarily making a series of short trips? If it's the latter, you may have a DPF filter that hasn't been able to run a complete cleaning regen cycle. If that's the case, drop the truck down a gear or two and run it a little harder for 20 to 30 minutes so that the exhaust and DPF filter can get hot enough to complete its regen cleaning cycle.
If it's a DEF indication and since the indicator is still lit after adding DEF, then you'll need to pull the code to see what's happening.
So sorry about the timing of your problem and I hope that it's a quick and easy fix!