Hello Doctors, My son who's 7 year old 4 weeks back had a blister in his right foot 4th finger, this has now developed into a thick dark 2 mm lesion, doesn't look like it will fall off anytime soon either. Does anyone recognise what could be this? He had issues with his shoes that was slightly cut off at that finger area, which we have changed, but most likely it could be a trigger. Any help is appreciated.