Why there's a wart in my tongue?

Biopsy: Real warts are viral growth with in your skin. Virus could have been introduced due to a trauma, accidentally or by the habit of biting your tongue. If grows fast, it has to be removed and sent for lab exam (biopsy). It may disappear spontaneously, but is better to check.

See a dentist: It might not be a wart. I would recommend you see your dentist to get a referral to an oral surgeon to have it removed and biopsied, then accurate diagnosis would be known.

Papilloma: According to your description 'wart in my tongue', it is very likely an pale overgrow tissue with a stem grown on back of tongue? A 'papilloma' is a reaction from an ebvirus infection. Please consult an oral surgeon for further evaluation.