Itchy Yorkie, HELP!

About 2 summers ago my six yr old yorkie, kiesha had a stroke. i was drying my hair when i heard a thud or a plop on the floor. i noticed she did not move after jumping off the bed. i picked her up a few inches off the floor and she just fell to her left side. i bundled her up and took her to the vet as fast as i could. i tryed to keep my composure, but the vet said she probably had a blood clot pass through her brain or in her brain. the doc gave us some steroids in pill form, to keep her brain from swelling. a few months down the road she began iching perfusley. she only seems to scratch on her left side from her ribs to her little legs. she is also extremly ichy from her shoulder blades down to the base of her tail. ive been to three vets so far. they say it could be allergys or the nerve endings from the stroke. first we tried this shot which stoped the iching for one week. then we tried children's benadril whiched seemed to work but not over a year. i try to relieve her iching the best i can, we try head n shoulds sometimes, and this shampoo with aloe and oatmeal, but they only give her slight relief for a day or too. i have not tested her for mites, maybe thats it. the funny thing is that the iching will come and go. at first it was a year straight. then it would go away for a little while and then come back. over this winter she seemed to be a lot better. good enough for me to forget her past suffering, and about a month ago bam! i feel like bad mother, there is nothing i can do to help her. she is sufering and i can see it in her eyes and i love her. she is my best freind. can anyone help? please.