What could be causeing my tongue to be numb and swollen?

Many possibilities: I can give you some ideas, but a doctor needs to see you and examine you and know more about your history. Possibilities: allergy or angioedema; your tongue might feel swollen (with no true swelling) because of a nerve problem; neurologic issue like stroke, ms; tongue or oral cancer; infection like herpes, etc. If your tongue is swollen enough to affect your speech, get to a doctor immediately!

Many things: This can be due to a food allergy. It can also be dueto certain medications or a candida (yeast) infection in the mouth. It may simply be dueto dehydration poor saliva production. If it persists see your doctor or ent.