Thank you for getting back to me. I think you are right to want to take him to a vet, but I'll give you a few suggestions in the meantime.
I’ll start with a first aid measure.Buy some Pedialyte (yes, the kind for human infants). Prepare a shallow bath consisting of 1/2 water and 1/2 Pedialyte. Soak Thor for about 20 to 30 minutes twice a day. Reptiles can absorb the electrolytes and fluids through their skin and vents (where droppings pass out), so make the water deep enough to cover the vent. Be sure to supervise closely.
I would get rid of the sand. Pet stores often recommend it, but it does frequently lead to serious health problems, including impaction. It’s also a leading cause of eye infections, respiratory irritations, and skin problems. I recommend reptile carpet or ceramic tile as a substrate. Here's a reputable site where you can read more:
It's possible Thor has become a bit constipated from accidentally swallowing sand.
Those dark lines on Thor's underside may be the digestive tract, but they may also be actual veins. All the internal organs and blood vessels are more visible on albinos. You will want to ask the vet about this to be sure it's not a sign of something wrong.
I would also increase the temperature. Leopard geckos do best with a warm side at 88*F and a cool side at 82*F. These temps should be maintained day and night.
The soaks, warmer temps, and removing the sand will be all you can do on your own, but these measures will support Thor until you can see the vet. If you don't already have a vet, this link will take you to a directory of reptile vets:
If you have more concerns, just let me know. I hope Thor will quickly reach a full recovery.
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