leo gecko very, very ill

Question
Gecko is approximately under a year old (just a guess!).  Has slowly lost weight over a couple months - had started to get a fat tail around 4 months ago, but then the fat tail went away.  Currently has "pencil tail" and extremely lethargic.
Took Yoda to "herp vet" - only one I could find.  Vet gave me the dry food to mix with water (two parts food, one part warm water) and try to feed two to three times per day to increase weight.  Yoda is curently at 5 grams for weight.  Also told me to get UVA/UVB light to help with calcium absorption.  I did and am doing all of this (although I question the UV light in a nocturnal lizard?) and am feeding him two to three times a day with dropper.  He definitely has the dark spot on his belly, which I can assume to be impaction judging by internet search and some pics I found on line.  The vet DID NOT KNOW what the dark spot was.  (herp vet???)  Sometimes he is so lethargic you can put him on his back and he won't move for a minute!  I have also tried a couple warm water baths in the past two days.  He seems to perk up with the baths, but not much.  He is currently under a 100w lamp during day and a red "night light" at night.  Under tank heater on one side (where the overhead lamp is, too).  There is reptile carpet for substrate, a bed of wet moss, a dry hide, and a shallow bowl of fresh water.  Daytime temp stays around 85-90 on hot side. 40% or so for the hydration.  This little guy is breaking my heart - he's my daughter's gecko but because she's 9,  I am primary caretaker.  We love the little guy.  Not sure if I should up the baths, or add olive oil in drops to take internally.  
Thank you for your help.  I worry it is too late, but will be willing to do anything.

Answer
Hello Kerry,

Do you have any pictures of her?
Which UVB are you using right now?  What type is it a fluorescent tube bulb or a compact/coil light?  What brand is it?

What type of thermometer are you using & what is the tank size?  The 100 watt seems a little high to me.  
The carpet should be fine.  What food does she eat, or had she been eating, other than the dry food mix?  Were you feeding him mealworms, or crickets previously?
What calcium supplementation do you use?  
Did they not do a fecal exam on her at all?  It sounds like it could possibly be parasites or worms with the severe weight loss.  
He is very tiny.    
When was the last time that he went to the bathroom?  
If it is not stressing him too much, you can give a short bath yes.  You can add a drop of olive or mineral oil into his food, daily as well.
What do you feel could have impacted him?  Was he on sand in the pet store?


Let me know how he is doing.
Tracie