odd sensation in mid back

I have a recurring odd feeling on the left side of my back about halfway up. It is very difficult to describe but feels about the size of a fist and is a "creeping", crackling sensation (almost feels like a "tens" unit....pins and needles). It is not something on the outside but feels like it is inside somewhere. I recently went on vacation and had a bad lupus rash from the sun. I noticed that during that time, when I layed down, that area "pinched" when I breathed in. I asked my rheumy when I saw her and she said if could be a mild case of pleurisy from the sun exposure. I have been noted to have pleural thickening. However, most of the time it is not a painful feeling, just that odd sensation. Just wondering if anyone else experiences it. Also, I was on the steroid cream for my rash. Does that make anyone else thirsty or is it just my imagination? I also promptly got a yeast infection right after starting it...something I rarely get. Coincidence? Thanks for any feedback.