Wow - I can sympathize with you - I have been struggling with this myself (the fistula part). My son is 20 months, and I have been hoping over the past year and a half that it would heal on it's own. I count myself lucky that I have not, yet, experienced any fecal incontinence, only the gas you mentioned, but I agree that the emotional toll is still intense. Especially the fear of having a c-section, or not having another child at all. I had wanted one more, and wanted to have a less traumatic birth than my last. I pushed for two hours, suffered third degree tears, and took a long time to heal. Because I do not have health insurance (but will in a few weeks!), I have not yet consulted a doctor, but have pretty much diagnosed myself via the internet... I've never heard of the 'dimple' as opposed to a hole, but in my research have found some interesting points. First, someone on this site, at one point, I think even a midwife, had suggested that having another vaginal birth could actually heal a small fistula. Other people have disputed this vehemently, and feel that a vaginal birth can only cause more damage.
I also found that this problem is more common than anyone knows, probably because it is such an embarrassing problem that no one wants to discuss it. Now that people chat online, and can maintain their anonymity, it is becoming more openly discussed. And, it can most certainly be caused by a poor repair of third and fourth degree tears. Mine was only third, but not far from a fourth, and I really felt like the doctor did not take his time repairing it. However, the epidural had worn off while I was pushing, and so I could feel him sewing me, and I remember crying out a few times, which probably rushed him. Still, several people have said that OBs do not have the experience to stitch when a tear reaches the anal muscle or tissue surrounding it, and some suggest that a colo-rectal surgeon should make the repairs in the these situations.
I, myself, am still debating surgery also - obviously I will have my OB check it out first, and discuss it with him, but I am curious about other options. One person had suggested doing Kegals (I've tried, I'm not sure they make much difference), but I have been wondering if there is any type of alternative approach, homeopathic remedies, massage techniques, anything outside of surgery.
Anyway - sorry this is so long - I hope some of it was helpful - I have only just started talking about this with anyone - I agree though - it is something that is difficult to think about, especially when the information you get from people is so contradictory.