aww I am so sorry your Tigerlilly is experiencing this
My kitty Mittens lived to be a wonderful 18 yrs old and was my 1st baby so to speak. I got him when I was 9
It is so hard to watch them get older and start doing things you don't know how to handle.
I agree that I would take Tigerlilly to the vet. Maybe they could keep her for a 24-48 hour observation so they could witness what you have been. I would make sure my cell was in my pocket or readily available to get a video clip of her doing this and take it to the vet. Hopefully medication can help your kitty and you guys can have many of wonderful years left together