Hi! It Started Yesterday Morning Where I Am Breaking Out

Hi! It started yesterday morning where I am breaking out in my mouth. It's not sores. More like welpes. Started on top of my mouth then it went away.. Now a day later I have them on my cheeks on the bottom area. It seems to get worse every time I eat anything. I took one Benadryl last night and nothing happen. I don't know if it's a good allegories or what? I need to go if I need to go to dentist or the emergency room. Please help.