Yesterday afternoon my back muscle started spasming really badly, and I couldnt look down or move my back for a while, it was like a sharp pain like the muscles were tearing apart.

today just before I had some brown discharge on my liner, enough to soak it up fully and when I wiped, i had a light pink discharge along with normal clear discharge.. is this normal implantation bleeding? (is it normal to have back muscle pain w I.B)?