If the vet has ruled out health issues, (for example, respiratory stuff would impact how much she exerts herself) then maybe something like this would fire her up, it's got three speeds plus a random speed mode: https://www.amazon.com/Petlinks-Mystery-Motion-Concealed-Colors/dp/B006ZL3578/
Is it around feeding time? I read that cats have something in their stomachs that is produced around the time they are used to being fed to help break the food down so it may be being produced at that time so it’s giving them a tummy ache? Alternative to that if they just need attention what about an automatic toy to distract them so you can go to sleep? There is this you could turn on and leave on as a distraction - automatic spinning cat toy thing
Petlinks Mystery Motion via Amazon $24.49 Edit: It is Prime eligible as well.
Id try out some new toys. If you're busy something like this could work https://www.amazon.com/dp/B006ZL3578/ref=cm_sw_r_cp_apa_i_5YaaGbCEW114N?_encoding=UTF8&psc=1 Cats get bored too.
I live in a super small space and my kitty had so much energy. These are some things that have made my boyfriend and i’s life easier.
This cat toy is great when you’ve played with your kitten a lot but they still have a ton of energy. We turn this on in the early morning or when we are trying to sleep if our kitty (now 6 months old) is feeling active, or if we are preoccupied and cannot play when she wants.
Also, cats usually prefer running water, so I have this cat water fountain that she loves loves loves. Our kitty used to get her food in the water, and since this is taller than the food, it’s not a problem anymore, and it also constantly filters the water and isn’t loud.
Petlinks Electronic Motion Cat... https://www.amazon.com/dp/B006ZL3578?ref=ppx_pop_mob_ap_share
I’ve had to buy two of these because my cat loves it so much!!