Wonder if it could be a yeast or fungal infection? For relief, try using a sitz basin. Sitting in very warm water will bring relief and the warmth will increase blood circulation to your insides, which might heal as well. It doesn't sound like a fissure, which you would definitely recognize as shards of glass burning with every BM. Unless it's the start of a small fissure? Sorry I'm not much help, but just some suggestions.