My vagina and anus feel very sore, particularly when I wipe them and a little when urinating. I'm also having yellow vaginal discharge with no odour.

?infection. Your symptoms sound like they could be due to an infection. You would be best served to see a dr/health care provider for an exam and some testing to assess for a possible urinary tract/vaginal infection. The anus pain may be a sequlae of the infection as well. Best wishes.