My first guest would've been hemorroids like you said, but if it's white patches, then no. I just hope it's not an infection where pus is forming inside, I don't know but it could be serious especially if the pain doesn't go away and the patches worsen or get bumpy, you might want to go do a check up. You can go to an emergency clinic and wait if you really don't want to go to your regular doctor. You'll be less embaressed if you don't know the doctor, plus they see so many cases like these, similar and even worse that it really doesn't matter, the most important thing is your health first.