Doctor said i have an anal fissure and gave me antibiotics/cream/suppository. almost done with my antibiotics and though my pain has slightly reduced and now can sit on a donut pillow, i still feel it. when should this heal and get better?

Some anal fissures will not heal with the treatment described, and may require more extensive surgical repair. Get a referral to a colo-rectal surgeon if your symptoms persist.

But just as important is to be sure to be eating a high fiber diet and most importantly drinking 80-100oz of caffeine free, alcohol free fluid daily, more if you workout strenuously. There are other meds that work better but if no repsonse to above after2 months you may need surgery to avoid complications such as an abscess. See a colorectal surgeon.