I am so sorry to hear about Skectchie as we are going through a similar thing with our cat Ridley. She was also diagnosed with either IBD or lymphoma as well. She has been on prednisolone and tylosin for two months now, along with eating kitten food for the extra calories, and she has done awesome. I have also started giving her B12 shots weekly. She has already gained about to 2lbs and has gone from vomiting daily to twice in 2 months. I am not sure if your vet has tried this treatment yet, but it was so great for Ridley. Best of luck and I hope he gets better.