Vaginismus but anal (medical concern)

So i just shit blood and thats supposedly common of someone with hemmorhoids. I dont think thats what i have but im concerned my doctors going to check because of that symptom. I seriously cant even handle the thought of anal penetration. Ive tried just putting a finger in there but even thats too horrifying to me. How tf am I supposed to handle if the doctor insists?? Im going to cry.