Well... its possible there are some factors that could be contributing to him not eating:
1. How warm/humid is his cage?
2. Where is his cage positioned in the house? In a high traffic area or a low traffic area?
3. Do you have any dogs, cats, or other animals that are around his cage that could be causing stress?
4. Have you tried leaving the food on a plate in his cage overnight?
5. Have you tried feeding him live pinkies?
If I remember right solomon's can be a little picky...
I would suggest taking him to a veterinarian instead of a petstore, as most petstore employees don't know what they're doing, especially with reptiles.
Pinkie-pumps are also an option, provided you can find one locally in time. Kinda a nasty idea, but it works well.
Good luck
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Current Collection:
0.1 Antherystic elaphe guttata guttata - Corn Snake
1.0 Elaphe vulpina gloydi - Eastern Fox Snake
0.1 Leucistic elaphe obsoleta linheimeri - Texas Ratsnake
1.1 Morelia spilota cheyni - Jungle Carpet Python
0.1 Tiliqua scincoides intermedia - Northern Blue Tongue Skink