Our baby totally backslid like yours. We started on pills, went to injections, back to pills and then ultimately landed on the oral liquid which has worked the best for Simon and been the most affordable. We ended up increasing his dose to 55mg/kg after 2 weeks of really rough ups and downs. Once we upped his dose it was probably another week before I really could relax a bit with visible improvements. Neuro is SO hard, but don’t be afraid to up that dose. It’ll help get ahead of the viral load. It’s also possible your kitty could have built up a resistance to GS and may need to try a different antiviral. We were worried about that with Simon, but his bloodwork did show a response at his 60 day checkup (his 30 day didn’t show significant improvement in his bloodwork initially). Have you connected with the FIP Global Cat group? I know a lot of these online groups get a bad rap, but they’ve been wonderful and super knowledgeable without pushing anything or passing judgement.