My podiatrist popped a large blood blister on my foot 3.5 wk ago. The area is still numb from the procedure and the part she cut to drain is black!

Go back for follow . Up. All you state is they popped a blister, this would not involve anything put puncturing the roof of the blister which would not cause any residual numbness, so I do not believe the numbness is a result of anything the doctor did. (If that's what they did). The black color may be an eschar or scab like lesion which again may be completely normal and will heal over time o r the doc can clean it.