Black/dark red blister under tongue

Hey everyone, noticed a small blister in my mouth today. It's under the tongue and it doesn't hurt, so I'm not sure how long it's been there. My doctor is on vacation. Any ideas what it could be? See the attached photo.

2-3 weeks ago I hit my head in the swimming pool and 2 days ago I had 5 glasses of wine. Not sure if this information is any helpful, but I thought it might be good to share. 

Hi there,

I’ve also had these little blood blisters under my tongue several times. I’ve had my mouth checked numerous times as I’ve had an ongoing dental problem but neither Doctor nor Dentist has ever commented that they’re significant.

Not sure this helps you but at least you know you’re not the only one, and it’s most unlikely to be anything serious. 

Regards

Jane 

Hey, yea, thanks a lot of your response, it disappeared after a day or two. Not sure what it was.