You are doing a fine job! As others have said, try for Zithromax and make sure his pain is addressed -- hopefully the Metacam has done that, but he might need to try something different.
With regards to him not eating for himself, my Tubs had this exact issue after being syringe-fed for a long time. Trying some of the things suggested
in this thread might help, and I know
@Adelle had
a similar issue with her Fudge; for both of us it just boiled down to having to be strong-willed -- if you know the pig can eat but won't, you might just have to entice them and wait it out. Definitely get the teeth checked out first though; a pig who's keen to be syringe or spoon fed but can't eat pellets and hay is a bit suspicious (though this was my Tubs at one point and he had no teeth issues)! It could also be he's still sore of feeling ill due to the abscess.
Things that encouraged eating for me included: giving loads of different kinds of hay (Ings, timothy, Readigrass, oat hay, B&M timothy which is very soft, some very green German hay that I had imported... I was desperate at that point!); sprinkling Avipro or other probiotic powder over absolutely
everything as Tubs loves it; feeding grass; trying new syringe feed (and if the pig liked it, mixing it in with soaked softened pellets for them to eat themselves); giving Fibreplex in case it's a gut issue (and offering loads of cardboard); trying different pellets; and getting the pig a friend (though I don't know if that applies in your case -- Tubs was due to be bonded with some babies so I eventually did it while he was still unwell and they encouraged him to eat a bit). The biggest thing was
time -- as soon as your pig can eat a little for themselves, reduce the syringe feeding and wean them off accordingly... it takes quite a while for them to get back to normal.
If it makes you feel better, Tubs and I have a closer bond than any of the rest of my pigs, due to my looking after him over his couple of illnesses. Iggbutt may be unhappy about it now, but he won't hate you in the future, I promise. Offerings treats or grass after any horrible medical thing is often a good way to make the bad memories go away