Kaywinnet has the right idea here but this is an extreme allergic reaction here or even the onset of mouth cancer so she needs to get to her DR or ER ASAP as this is beyond waiting and will only get worse so as her friend get her help now or even tell her Parents as this could be a starting matter of life and death at an early death. She may get mad but one day she will thank you for it as mouth cancer is extremely painful. Good luck
My fourteen year old friend smoked a roll up cigarette. She did not share it with any one and a couple days later, on the top of her mouth, there are like blisters and when we squeeze them with tweezers, puss comes out inside of her mouth up the top behind her teeth along there
IF someone else rolled it, there might have been something else in it along with the tobacco, or maybe if it was very cheap tobacco she might be allergic to it, or maybe to the cheap rolling papers.