What Causes Middle Back Pain With Crystallized Discharge?

hi my name is claire williams and i am 31, i recently went to my doctor with middle back pain in both my sides. it made me feel sick and very light headed, he sent me to hospital were they took blood and done some test, but the only thing that came back was a slightly elevated blood test that could mean that i may have gallstones.
they gave me diclofenic and tramadol to take and said that the back pain was probably musculuar.
a week went passed and i was still no better, but i thought i would have a couple of gin and tonics to ease the pain, well it worked and the next morning i had a crystalised discharge on my pants, and the pain had gone.
could this have been a small kidney stone that i managed to pass?