What to do about anal fissures that open even with soft poop. Is there something wrong with the muscles or the lining of the anus? Nitroglyc not work

May need surgery. chronic scarring from fissure healing and tearing may not heal - too much topical steroid can also cause fragile anoderm (anal skin) that tears easily.
Metronidazole. Is the best conservative treatment.surgery rare. Would recommend seeing a GastroSpecialist.