Thank you for writing to us.
I think that you have a blood collection under the skin of the shin. This can happen when you get an injury on the shin. This injury will cause the blood to collect.
You can try to massage the area to help increase the blood flow and remove the blood. Also, ice the area and use NSAID cream to reduce the swelling.
It should resolve in 10 days. If it does not, see a Doctor. All the best.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.