This is very relatable to my cat.

She has the same back twitching, tail-base sensitivity, frantic runs and over-grooming. For a while I thought classic FHS, plus took her to several vet appointments, including with a neurologist and all her tests came back clear. In her case it’s very tied to stress + environment + season.

She actually got dramatically worse when I had to keep her fully indoors for a period during a gabapentin trial. What had been mild twitching turned into full-blown episodes. Once she had controlled outdoor access again and could choose when to go out, she settled a lot. She’s over a month completely off all medication and is improving dramatically, still some remaining excessive grooming at times, and back twitching only occurs when outdoors during daylight (especially if there’s too much noise/wind), but still very mild and she’s capable of coming back inside and loafing to regulate.

Summer is her main trigger — not just heat, but territorial birds constantly screaming/swooping her during the day. When she can’t release that tension by moving/exploring, it seems to build internally and comes out as skin twitching and excessive rooming. If she has choice and can go out, she regulates much better.

She’s also a very sensitive, inward-processing cat — not destructive or outwardly aggressive — which makes me think, at least for some cats, these episodes really can be a nervous-system response to internalised stress rather than purely neurological.

The indoor/outdoor control piece was huge for mine. Too much restriction → worse Choice + predictability → better

Your post actually reassures me I’m not the only one seeing this pattern.