Well, you did have him eating for you you said. Then he just stopped. I mean, you havent changed anything im assuming which is the weird part. All of my snakes will go a couple weeks without food when shedding. Pat is the exception as he shed in 8 days but went without food those 8 days.
If you changed anything in the cage between when the snake was eating and then wasnt, i would change it back. And yeah, you might want to try and live pinky.
It's just so weird how he was eating when you got him but then quit. Babies can do downhill fast which is another weird thing as it's been 4+ weeks since he ate? And he doesnt look that bad.
Only thing i can think is just use the pinky to try and piss the snake off by rubbing him, banging on him and stuff but not around the face and hope the snake grabs it from maybe a pissed of defensive bite but then will turn into a food response.