Just to set out I haven’t been to the drs as I really hate going to the drs as I am overweight and worry they will bring everything back to that. I am 35 and female and have no health issues. 
for a few weeks out of the blue I started having a really sore bum (not itching) just painful and uncomfortable, it has gotten worse, struggle to sit / walk/ move about as it is constantly throbbing. I’ve can’t see or feel any piles. I have started taking a fibre drink but going to the toilet has become very painful. I have started taking anusol and my poo the last time I went was white. The pain is high like an 8/10 and constant. I have had a little bit of pink / brown mucus blood (which I don’t normally have) but also was either side of my period so could be linked to that. Just to add - I don’t have anal sex so it shouldn’t be any type of infection. 
my mind just goes to the extreme of worrying about cancer but I have no other idea what it might be? Any suggestions/ advice please?