What Could Black Spots On Mouth With Swelling Suggest?

i just noticed a black dot on the inside of my mouth. when i feel it with my tong it feels like a blister swollen. but it's black, i thought may be blood clot. i can't remember if i bit the side of my cheek or not. but if it's not from me biting, what else can it be? I'm very worried ... i am a female