Don't worry, no surgery will be needed. This happens quite often in toddlers who tend to get constipated due to not developing regular bowel habit. The passage of the hard  constipated stool creates a cut in the anal canal lining which is called the fissure Management prescribed to your baby is correct. We have  to ensure that stools passed are not constipated by giving mild laxatives. For the fissure to heal we have to give the sitz baths. For pain  not to happen while passing stools  we have to apply an anesthetic ointment on the fissure. But most importantly we have to ensure a regular timing for the stool everyday. The best timing would be after a major meal maybe breakfast or lunch when the pressure on the bowel would aid in the passage of the stool. The process of healing will take time and perseverance from your side so you have to be a bit patient

Greetings it's not serious issues , once the fissure heals the baby will be fine until that u can continue the same medication. For further information kindly consult me