Friend, the dry stool you note is possibly due to less water consumption, non veg food and no fibres supplemented so also sub clinical hypothyroidism.If anal fissure is just beginning, reverse all these situations i narrated before in your routine and use local anaesthetic like lignocaine gel before and after and sitz bath. You may also have some broad spectrum antibiotic if severe pain and fever are there ant time. But if you had this problem on earlier occasions see a proctologist to help you .