The first time it happened, she was jumping from the bed to the floor, and along the way flipped over and landed on her back, flailing with all fours in the air for several seconds seemingly trying to right herself. The second and third time happened today. The first time today I was holding her and she had a bout as I was about to set her on a chair. I tried to hold her still in my arms but she was twisting and turning in my arms (not trying to get away, it seemed almost involuntary). I noticed her heart was beating more quickly than normal and her respiration was up. (I figured she was scared from what happened to her). It happened again for the third time when she was just sitting on the floor. Any idea what is happening to her?
I know it is likely age related, as she is 18. She is an otherwise healthy dom. short hair, with no other symptoms.