I have a small red lump under my tounge it's not hard or soft and it's not sore what can it be?

See ENT: This "lump" can be many things ranging from a simple cold sore to something more concerning. If this "lump" has been there for awhile and isn't decreasing in size, i highly recommend that you see an ENT (otolaryngologist) for a complete head and neck examination.

Salivary duct: If it is one of two little bumps that straddle the midline they are salivary ducts or openings for your salivary glands. If it looks like a blood blister it is probably due to a minor injury as the blood vessels are very close to the surface under the tongue. You could have unknowingly "stabbed" the tissue with something hard or crunchy.