On and Off Backache. The back next day?

I am 27 years old, female, 54 weight, 5'6 height. I've have been taking aldactone from past 2 years now for my adult acne which got cured in its first year itself but then I stopped taking it. After few months, I got 1-2 pimples then I met my dermatologist and he again started me on aldactone. So the dose was 25-50, 50-50, 25-25, now from today i started taking 25 mg only. I also have hypo thyroid for which I take 25 mg thyronorm but my thyroid is controlled because I am a fitness enthusiast and I eat healthy. So from past 4 years my weight is same. But since February of this year my weight varies between 51-53 kg. I am not working out due to work schedule and backache. Can you please tell me what I am doing wrong. Why do I get backache in one point for whole day then on the other point of the back next day? I also took muscle relaxant as prescribed by the doctor for 5 days and got my upper back scanned too and it came normal. It's been more than 20 days and I still have backache.