Anyone? Cm question

So has anyone had very little cm before a bfp? Had a brown discharge for about 24hrs very light that was about 40hrs ago now Bfn this morning AF is due tomorrow. Lower Back is constantly aching which I don't get with AF I usually get back pain only when i cramp this is all day the last 4 days 😧 started to get sharp pains in my boobs and tinges in the pelvis 😳 I'm just so frustrated feel like my body's playing a awful trick on me 😢