Yes, the 5.0 is too weak, especially when it's placed 2 feet above.
What are you using to measure the ambient/basking temps? The basking temps should be no lower than 95 but no higher than 115 (some beardies don't like it too hot).
What do you feed your beardie? How often is he getting live feeders, and what are they?
You mentioned "island" -- where might that be? And what are the average temps there?
Any vet should be able to run a fecal test; it doesn't have to be a herp specialist. However, if you're planning on taking your beardie for an examination, you'll have to find one that specializes in reptiles.
Last, but not least, when was the last time he ate anything? Had he been pooping, or stopped that as well??