Have you talked to anyone at the pet store
or a garden center that specializes in fish ponds? Perhaps they would have more suggestions to add. Sounds like the little fella had a touch time of it and I'm glad to know that he is doing better.
I agree with Sasami that he should be getting a better balanced diet that just peas - although if that's all he'll eat right now you can't very well force a fish! I've never had a fish pond but have had experience with aquariums: as I'm sure you've read by now all the cloudiness and dirty looking water is the water "cycling" to get all of its components at the right proportion. Normally our tanks would take about three days to go through their cycle.
Another thing that more than one veterinarian has told me about dealing with sick fish is to put a little salt in the water. I'm not sure what this does, but it does seem to help. How much would depend on the size of the tank he's in. We would put about 1/4 tsp in a 10 gallon tank.
Hope he continues to do better. Sounds like you are doing a great job with him.
Attachment?? Phooey. I think I could get attached to an earthworm if I had to try to take care of it! Isn't that the reason we're all here? If you don't love 'em you don't need to have 'em!