In this case, Kim’s mother’s burn formed blisters. These blisters are often closed and fluid filled. Recall that a first-degree burn is characterized by redness, not blisters. Why do you think a first-degree burn does not blister?

A first degree burn affects the superficial layer of the skin.

Explanation:

A first-degree burn such as a sunburn, is a burn that affects the outermost layer of the skin. It's referred to as a superficial burn. The effects of first degree burns are generally mild, however few cases could be worse than the normal redness and non-blistered wound seen in most patients. These type of burns can be treated with home remedies and mostly do not require medical treatment.

when you rub, you also apply pressure, that pressure can urge the poop to come out. i think that when your rubbing, you also might be slightly breaking it up and that can further fill the stomach.