You do not have to put the Diltiazem inside. I only used it on the outside (I had Nifedipine), as that is where my CRS told me to use it. It takes time to have an effect, or that is what it did with me. I had a special compound without vaseline and lidocaine, so possibly you will have a quicker response to your medication. I can't really say that it did much for me, but that is possibly because mine is chronic, and once at that stage it is very difficult to heal.
I have resorted to using Sitz Baths in a serious fashion these last few days (been a bit slap-dash previous to this), and it seems to be helping with the pain. I also take 0.12mg Lorazapam for the spasms. Other relaxants did not work for me.
About being squemish! That flew out the window for me long ago with this darn thing
Push for getting a CRS to look at you. GPs are not the best - wherever you are in the world - for fissures. They get convinced we have hemmies no matter what. And my doc here in the States wanted to give me a concentration of Nitro that they put on heart patients to put on my rear!!! Never presume that because they are doctors that they know it all.