Please do read pinpin and Davo's reports of their surgery. The are really two of the best ones on here, written clearly. Also, as I said before, the vast majority of those who come here have had surgery, left the forum and are busy getting on with living life again

It is probably a good idea that they do a colonoscopy so that they can make sure that nothing else is wrong, and as you said he is an experienced surgeon I am sure he is doing what he thinks is best. Another good thing; you have caught this when the fissure is relatively acute. Much the best. Many of us leave it much too long before seeing a CRS.
I too used both Nifedipine and Diltiazem, though the are both close to being the same in that they are both Calcium Channel Blockers. Eventually they both gave me a rash so had to stop. I never tried Rectiv, which can induce headaches in most people. I never used Miralax. I use Milk of Magnesia. What helped me through it all was the ability to get through the night with the help of a very low dose of Lorazapam. Don't know what I would have done without it.
Anyway, good luck with your colonoscopy.