My Father Is 85 Years Old. He Has Dementia. In

My father is 85 years old. He has dementia. In March he had the flu and his dementia has become extreme since then. He forgets things from 5 minutes ago, is irate, doesn't sleep much, and has started to have problems remembering things from the past and finding the right words during conversations. He can no longer drive, and I cant leave him alone. Any suggestions?