Crohns disease, just had 2 perianal abcess drained last week. now having bad pressure in back passage and when passing stool it's thick mucus instead?

Crohns Disease: All of the above symptoms, the abscesses, the rectal pain, and the mucus in your stool are indicative of the possibility of continued active inflammation from the Crohns disease. You likely need to have your medication either adjusted or changed. I would make it an appointment to see your gastroenterologist as soon as you can. Good luck.