Poor guy, and poor you.....I hate to think that you will have to carry him up & down stairs on any frequent basis.....I guess if it were me I'd be trying the vet's for meds & then try each day & see if he feels like doing the stairs on his own before I'd try lifting him......I can't remember if he is on any meds for arthritis? My Molly is on Galliprant because she can't have Rimadyl due to her rising ALT levels. The Galliprant is really helping her so far. She is too heavy for me to lift with her harness, but dh has had to lift her into & out of the motorhome because the automatic stairs quit working. She doesn't really like being lifted though, & thinks she can jump, so that made it harder for him because she has her legs all kicking, etc. But now he made her a set of shallow steps to go in & out & she goes right up & down, looking quite happy & proud of herself! She was given Gabapentin when she was having more trouble, also, but hasn't needed that for quite awhile now.
Is there any way a ramp might be easier for him to go up & down?