Hey Jenn, the exam under sedation sounds like a good idea. They can get a real good look that way. I had it done in the ER on the one day when the fissure kicked my ass the hardest (I couldn't walk that day and had to be carried out of work in tears by coworkers -- it was THAT bad) and didn't feel a thing.
I wouldn't doubt that yeast infections can thin skin and increase the likelihood of a fissure. I'd know because I've had a persistent penile yeast infection for a while now and it unfortunately definitely ummmm "thins skin" if you catch my drift (hint: I'm uncut and think of the affected area ... so yeah :().
But the Tinactin thing still just seems bizarre. I do think it could decrease itching because most topical antifungals are designed to minimize irritation as well as either kill or stall yeast. Trust me, I've used about 15+ different antifungal creams on "other areas" over the last half year. Tolnaftate (the active ingredient in Tinactin), Nystatin, clotrimazole (Lotrimin), miconazole (Monistat or Baza cream), terconazole, etc. etc., you name it, I've tried it, and sadly probably in a bunch of different concentrations and formulations. A bunch of oral antifungals too like fluconazole (Diflucan), ketokonazole (Nizarol), and itraconazole. The oral ones are actually much stronger (just not normally used except for severe infections since they're hard on the liver) and one would figure that if yeast caused fissures, these would be even more effective and should be on the short list of things to try, but they're not...
BTW I surfed the Web for hours during my fissure saga and tried a multitude of magic cures. You should see my medicine cabinet. I have all manner of things in there ranging from special cleansing solutions to tea tree oil to lubricants that I applied before I went to poop. Okay, so I never tried the Dr. Wheatgrass thing, but I'll admit that I thought about it :) So I totally understand the search for a non-surgical fix lol. But just be careful if you try anything because some of them can make things worse. I never tried Vick's Vapor Rub for my butt problems, but it does have soothing properties elsewhere and happyass also has an "experienced fissure ass" :) so I'd be fully confident in his recommendations

BTW funny story about the aforementioned day when my fissure sent to the ER: I was fine that day until I went to take a dump during late afternoon, and the stool happened to be a real hard one. After the poop, I couldn't even bear to pull my pants up or move from the toilet for like 20 minutes. Finally, I mustered the ability to unlock the bathroom door and called my boss on my cell phone to bring me my Vicodin and ibuprofen. He did and handed them to me with my pants still down. A few minutes after taking the painkillers, I managed to pull my pants up and hobbled back to my desk and waited in agony for another hour until my wife could come to work to pick me up. When she did, there was no way for me to get down the stairs, so a coworker had to carry me on his back (breaks my top 10 most embarrassing personal moments). As we're about to leave through the front door, two housekeeping folks (a couple) were just on their way in. They only spoke Spanish and it was plain as day that I was in agony because I kept crying and wincing with every stair and kept clutching my backside. Well, I speak some very basic Spanish and could hear them talking to each other in a concerned and frantic tone, saying "oh look he has a back problem, yes, yes, it's just like when our friend broke his back, wow that's so terrible." Worst part is that after that, they came over and started consoling me and telling me that it would be okay and that their friend had the exact same problem before LOL. Ok so you kind of had to be there to get it, and I definitely wasn't in any mood to appreciate it at the time, but in retrospect the entire thing definitely wasn't without some humor. And dang that was a lot of typing for a very short story.