Cat suddenly jumping, grooming tail/back, skin twitching — advice needed

Hello! I’m looking for advice about my cat’s recent behavior. My 4.5-year-old female cat (Devon rex) started having strange reactions about a week ago. As you can see in the attached video, she can be lying calmly on the bed and then suddenly jump up, turn around to check her back, or start excessively grooming her tail and back legs. She also has noticeable rippling or twitching of the skin on her back, almost like goosebumps. These episodes seem to happen randomly. The movements are very sharp and sudden, which makes me worry it could be some kind of nerve pain or discomfort, but I can’t tell exactly where she’s feeling it. Between episodes, she often seems normal. What conditions could cause this type of reaction? And which specialist would be most appropriate to see (general vet, neurologist, dermatologist, etc.)? Thank you in advance for any guidance. Video: https://failiem.lv/f/vfgxrxuq72  

Hello and thankyou for your insightful question; sometimes it is difficult to be sure from looking whether a behaviour is caused by pain or increased sensitivity to something eg on the outside of the building.  'Popcorning,' that action of jumping suddenly ( like popcorn as it cooks ), can definitely be associated with pain, as can suddenly aggressive grooming.  There are now various pain-scales designed to help you to pick up signs of pain in some cats, which rely on looking at the facial position. They take some practise to use but your vet should be able to tell you more about it.  Furthermore, because pain is so unpleasant and because most cats aren't forthcoming about showing it, many vets now would say that it's best to err on the side of caution and treat with pain-killers / investigate early when pain is still suspected.   Please do pay them a visit.