I have a juvenile lepered gecko I'm guessing his age at 3-4 months as I got him from a pet store in good shape. When I brought him home all was good I had him on reptile carpet at first but was not a fan of the look so I switched to eco earth which I thought could be passed normally. He was pooing normally but now isn't very often and when he does it is small and dry, he has been eating just as much as normal 10 mealworms or crickets dusted about twice a week so anything would help.
I have a leo and as he has gotten older and as he has gotten older, I have been feeding him less. With the reduced amount of feeding, I have noticed he does not poop as often. If yours is 3-4 months I think you should be feeding him more than twice a week though. A good video I watched for my leo on a feeding schedule is this: https://www.youtube.com/watch?v=leADmIhe6QI
Basically you should feed a 0-6mo every day, 6-12mo every other day, and after a year old they should be fed about every three days. The video also goes into what types of calcium and/or minerals you should use each feeding, so it is super helpful!
Hope this helps!