Spike - our bearded dragon , , ,

Question
we're worried about 'him' - he hasnt 'pooped' in approx. 3 weeks.  he also isn't too active - especially worried since we just changed out all of his lights - he usually gets 'cracked out' due to all the vitamins absorbed (?) that the new lights offer (that's what has always happened in the past)  he is still eating, but barely.  he seems depressed?  he also hasn't shed in approx. 4-5 months (he has been shedding about once a month since he has come to live with us . . . about 1&1/2 years ago.  the people @ the pet store said he may need electrolite drops in his water, but spike RARELY drinks water ? ! ? !  we love him very much, & are worried about him & his well-being.  we hope that you may be able to help us w/ our ?'s.  THANK U for taking time & all of your help.  :-)  p.s. should we plan a trip to the vet?   thank you, again.

Answer
I think a vet trip should be in order first.  If you have used bagged calcisands or vitasands from the pet shop, he may have become impacted by ingesting some.  He may also have parasite issues.  I would also let him have a bath at least once a week, this will help him poop and also get water into him.  Beardies normally lap at water misted on them, although my kids yake long drinks from their bath.