Hi, I developed an anal fissure a number of months after my diagnosis of crohns disease.
It was excruciatingly painful and I was given all sorts of creams etc to try and heal it but none of them worked!
My GI doctor eventually referred me to a surgeon who gave me a botox injection in the affected area and that healed it completely and I've had no bother since.
If this is something you haven't been offered, I suggest you maybe ask your GP or GI consultant for a referral to at least get a surgeon's opinion!
Trust this helps, good luck.