17 year old blind dog with dementia, help

Hi. I hope you are having a good night. I have an almost 18 year old rate terrier. he has dementia and is blind. he spends his day and nights pacing the apartment and bumping into furniture and walls. he was getting stuck in corners and in between furniture. he pees on the floor all the time and sometimes the bed. he only sleeps about 3-4 hours at night and wakes up and has to pee. then he sometimes will have to pace for an hour or so. when he poops he cant see it, so he will walk in it and smoosh it into the ground and also him. however when he is with me, he seems okay and we lie and relax on the coach together, but when I put him down he will pace and bump into things. he doesnt whine or bark, in fact he doesnt make a lot of noise. sometimes a little rumble if he gets moved or picked up. he had a vestibular thing where he would spin in circles in place but that seems to be better. Im just trying to see what I can do to help him and hopefully stop his pacing and make him more comfortable. I have brought him to the vet twice in the past year but I dont seem to get any answers from them. so I am looking to see if anyone has gone through this and how they helped. he is my world and such a sweet pup and I hate to see him like this.