I also have an itch in the middle of my back thats difficult to scratch. Ive had Bronchiectasis/MAC for now two years. Only nebulize with 7% and budesonide .5% both twice a day. I cant say what causes the itch. Age? Im 77.
However what does help is to put a lotion on the itch. Seems to help a lot. Maybe it dry skin. My itch is on the surface. Sue is inspiring. Eat a good diet.
For me its fruits and vegetables, mostly organic and since Im loosing weight, nuts, fish and eggs. Proteins seem necessary. Im currently looking into a protein whey thats plant based. Wishing you well. Hal