Big black lump in my mouth on my right cheek, it's painful and it spread to the left side i have black bloody stuff all over my tongue and rash onarm?

Hemorrhage: Black 'lumps' that 'spread' to other are areas may be submucosal hemorrhages. They may rupture and leave a bloody debris on the tongue. You need to get a blood test asap. Time is important in determining the cause of your symptoms.

Perhaps: Perhaps you are bleeding. Important to be examined by a Dentist ASAP. If your problem is not Dental, but instead is Medical, you will be referred.