My big toenail on both feet black and blue some pain what is this from?

See below: May be from direct trauma to nail causing bleeding under the nail. If toenails are too long &/or footwear is too short, nail trauma can occur. If u have vascular disease (pad) or diabetes, blood supply to nails may be compromised. See fp or podiatrist for evaluation & treatment options. Make sure nails are trimmed properly & shoes fit properly.

Black and blue: A black and blue toenail is usually due to trauma to the nail usually when running in shoe gear. If the nail is completely black and blue you may need to have the blood that has developed under the nail drained if this is causing you significant pain.