Welcome to the Forum! I am so sorry you are experiencing this! These type of problems can be frightening when you don't know what it is. There are a number of things it could be, including an abscess. Rectal abscesses are fairly common, but you don't really hear about them because nobody likes to admit they have had one. You don't have to have a disease like Crohn's to have problems down there.
You mentioned it is hurting and you are getting hot and feeling sick. I think this means there is an infection. I know from personal experience that you need to see a doctor as soon as possible. Whatever it is, it is getting worse. The bigger it gets, the worse it will become and the longer it will take to heal. I know it is scary but honestly the sooner you go to the doctor, the sooner you will be on the path to healing. In many people, abscesses are quickly drained and heal up never to return.
Please go to the doctor very soon so this won;t continue to get worse. A colo-rectal surgeon is the best doctor to see. And let us know how it goes!
Diagnosed with Crohn's in early 2007. Several peri-rectal abscesses and two fistulae with setons. Allergic to Remicade and Humira. Currently on 6MP, and vitamins D and B-12.