I'm glad he's doing better, yes the feline Leukiemia injection is kinda renowned for causing issues I think sometimes the triple vaccine is just too much for them and bengals are hyper sensitive to any type of stress. My two are on Natural Instinct I switched them due to my boy always having a runny tummy and within days the raw cleared all the issues up. If you want to switch him over I recommend using the Turkey one as it's easier on tummys than chicken and it also helps with stress due to the L-Tryptophan so it may chill him out a bit as well.
http://www.naturalinstinct.com/country- ... y-cat-foodhttps://www.amazon.co.uk/dp/B003ZJ8AF0/ ... biotic+d-c If he goes the opposite and gets a bit constipated which can happen on raw just add some Protexin Prokolin in his food for probiotics or get some Protexin Symbiotic D-C and sprinkle that in their food which I find works better if it's constipation.
Get some nutrical kitten it has added Taurine and really bulked up my tiny girl just mix it in with their raw once per day which is what I do with my two, you can get two tubes for £20 with free shipping here
https://www.vitamingrocer.co.uk/Nutri-C ... 309857.htm it takes about 10 days to come over as from the US but it's one that really works great.
If he really hates the vets and it's a planned trip you can also try some Zylkene in his food 2 days before which calms them down it's just a milk protein similar to what their mum secretes in her milk.
I understand kittens and tummy issues I've been to hell and back with my little boy his problem got bad after his neuter when he was given antibiotics for an eye injury and it got worse from there. Ended up finding out he can't eat commercial cat food or chicken without the runs I think it's maybe due to some type of filler ingredient but on raw he's great no issues at all.
Also they're really cute little guys so happy he's doing better.