loose

The bolt that holds the door hinge to the truck is loose so my door doesn't feel solid. I've looked up behind the dash and can't find anything to tighten. How do I fix this?

So I had the bed loaded down with heavy equipment. After I unloaded I started hearing/feeling the thumping sound coming from underneath in the rear. The truck only has 1800 miles and should NOT be doing this. I looked underneath and everything "looks" ok the spare tire seems secure. Any...