I have a flap of skin that came loose in my mouth last night, and it is located where the soft palate might be. any suggestions?

Trauma?: The most common reason would be some type of trauma, likely from a food burn. We're you eating pizza last night? There are some diseases that can cause soft tissues to blister up, but these are rare and you are a bit young. If it doesn't heal itself in a few days, you may want to see your dentist.

Flap of skin: I would see your dentist. You are very young so the possibility of something severe seems slight but i would get checked. You may have burned the skin on something you ate or even abraded it with something sharp like a chip and it is sloughing off. You could be reacting to something new you ingested. I would think of what you have done differently recently and tell the dds if it doesn't go away.