Actual age isn't so important because snakes may grow at different rates, depending on how well they eat, etc.- I'm trying to figure out his actual size, & snakes are hard to measure...
Thawing rodents properly: Doing this wrong causes spoilage & that may be why your snake is "fussy"- snakes can smell spoilage & unless they're a species like king snakes (that are willing to eat carrion), they'll refuse to eat spoiled rodents. Can't say I blame them...can you?
Thaw in COLD (or cool) water until rodent is thoroughly soft thru-out- feel it with your fingers to make sure.
Only THEN put in warm (NOT HOT) water to warm it up briefly before offering it. Honestly, I do NOT warm rodents for my spotted python & she always eats, but she's often eating fresh killed, not f/t, because I raise my own rodents. Instead of putting in warm water, you can also use a blow-dryer briefly to warm the prey.
I have a feeling that spoilage has been one of the issues in getting your snake to eat- their food should be "like fresh" which means not spoiled & not cooked. Whole rodents spoil in warm/hot water because their whole GI tract is present & FULL of bacteria that flourish when warmed, so the key is to thaw quickly: directly IN water is the fastest method but some scent will wash off the rodent & while I doubt that your spotted python will care, some snakes will prefer more scent than when rodents are damp (I blot any f/t rodents on paper towels- don't offer them dripping wet, lol), & in that case, it's easiest just to pinch-damage the nose of the dead rodent using your feeding tongs, right before you offer it. This also helps the snake target the nose for easy swallowing, unless you have a lot of "delinquent" snakes like I do, that often grab whatever end of the rodent I DIDN'T put forward!
The other big question is whether you're feeding the right size prey for the size of your snake.![]()