Difficulty shedding and questions about diet

About 3 months ago I bought a juvenile leopard gecko. I got him from a pet store, so I'm not sure exactly how old he is, or if he's even a male. I'm just guessing since it's too soon to tell. He is in a long 20 gallon tank with an UTH that keeps the warm side at about 80 to 85 degrees. The cool side stays around 75. The humidity is at 50%. I have a 60w Moonlite Reptile Bulb that I turn on at night. There are 3 hides: one on the warm side, and two on the cool side. One of the hides on the cooler side of the tank is a moist hide. I keep the water bowl in the middle. At first I had been using walnut shell as substrate, but soon replaced it with stone tile when I found out that sand-like substrates can cause impaction. His diet consists of mealworms and crickets. He isn't usually very interested in eating the crickets, so he mostly eats mealworms. At the pet store I was told that this is fine, but I know that places like +++++ don't usually know what they're talking about. I want to make sure I'm giving him a proper diet.

When my gecko was shedding today, he seemed to be having trouble getting the skin off because it was very dry. He would sit in the moist hide for a little while and then leave to go rub against things. During previous sheds he was able to remove all the skin pretty easily and quickly and it didn't seem dry at all. This time it took much longer and he seemed much more uncomfortable.

I am also concerned because my gecko has not been pooping as much recently. When I first got him, he would eat about 6 mealworms every night. Lately he's been eating less. 4 or 5 worms every few nights and the occasional cricket. Sometimes he won't eat at all. I think his tail is probably too skinny. It wasn't very large when I got him, but it has definitely gotten smaller.

He has been lethargic and just doesn't seem healthy. What can I do to provide better care for my leopard gecko? Does the diet need to be changed? Is there something about the tank setup that could be improved?

Ideally, the warm side should be about 90 degrees. Low temperatures could cause digestive issues and lethargy. Am I to understand that he does not have an UTH? This could very well be the source of his problems. Leopard geckos are accustomed to hiding all day and coming out at night when the rocks are warm from the sun. They evolved to use belly heat more than warm air, so providing them belly heat is extremely important.

For the dry skin, you can soak him in lukewarm water for about 10 minutes. Although I prefer to wet paper towels, place them in a Tupperware, place the Tupperware on a mild heat source (it should only be slightly warm) and place the gecko in there with the container sealed. It gets very humid and you can place something rough in there they can rub against. I've found doing this for about 10 minutes more effective than soaks.

Mealworms are a fine diet as long as they are properly gut-loaded and dusted. What do you use for supplements and how often?

I have an UTH. but it doesn't heat the warm side to 90 degrees. I feed him Timberline Vita-Bugs mealworms, which supposedly don't need to be gut loaded or dusted.

Do you dust with any supplements?

If you're UTH doesn't provide temps of 90 degrees, you should probably get a new heat pad. Proper heat is probably the most important fundamental elements of leopard gecko care.

Like Neon said if you can get the temp on the tile to 90 degrees that would be best for sure. A trick to help the heat pad is to put some aluminum foil between it and what ever it is sitting on (desk, table, shelf) this will cause more of the heat to go up into the tank. Some times tile needs a little more heat to really warm up. The warmer temp should help with pooping and lethargic.

As for his shed I would suggest moving the moist hide to the warm side, he might not be using the hide as much if it's cool. I always put my moist hides over the heaters. I feel the geckos spend more time in the hide if it's warm with the water cooler (75-80) they don't use it but when it warms up (85-90) they really enjoy it. This will also help the humidity in the tank but does mean I need to spray more water into the hide every 3-4 days.