Yes, as you can guess, I am great user of essential oils. He does and you do. Your problem is embarrassment. One man whose wife spat into a beautiful bowl of silk flowers in a high-class department store just apologized, offered to buy them and said, my wife has Alzheimer's disease. Perhaps you could work on saying the same.
People are very sympathetic in such situations.
You might look more deeply into your own feelings. They probably involve your real issues around your father being ill with this particular disease. This is an opportunity for you to work this through and come to a peaceful relationship with his disease. Not easy, I know, In fact, very hard, but very rewarding. Remind yourself, this is his disease, not him, then share that with others.