Just leave the ASF in there, in my opinion. My pastel, ED, went off feed for like 3 months, and I had to leave a mouse in his enclosure for a day and a half before he ate it. Its still been a struggle, but hes eatting regularly.

If you take him to the vet, you can ask for a tube feeding with some flagyl mixed in, hopefully it'll kick start his feeding response.

Just leave that ASF in there and don't bother him, he should take it in a day. He seems stressed, so let him go about his business for a few days. Meaning leave him alone, don't even open his tub for a day.