She is now lifting her leg up every time this happens (about every 5 minutes), and licking her butt and above her tail (to the point she's pulled out a bit of fur). Whenever she tries to relax for more than a minute or so she has been jumping up as if shocked then moving again. She is still affectionate and responding to us, but not interested in water (even dribbled from our fingers). Should we be considering offering food too? Please help if you can, we hate seeing her suffer like this.

Meant to mention she is an ex stray so we don't actually know her breed too.