HELP!!! sick leopard gecko!

okay well my girlfriend leopard gecko is sick! it happened over night! he was a wide awake social animal then one day she woke up and saw him lying there, thinking he was just sleeping she thought nothing of it...until she came home from work and he was still lying there he isnt a year yet he was born in november! he is VERY lethargic and has an extremely big belly (just got bigger then yesterday) and has both eyes closed most of the time! he is draging his body whats wrong and how do we help the poor little guy? :(

It sounds like you should probably take him to the vet...

What substrate, and temps?
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