Hi, thanks for writing to HCM.
I suspect that the swelling could be a HEMATOMA
(blood clot). These will generally resolve within 3-6 weeks spontaneously without any issues.
In Diabetic persons, there is a chance for the hematomas to get infected. Simple pressure bandage application over the swollen area will cause a reduction in size over a period of time. Moist heat fomentation will also help in resolution of the hematoma.
If you are concerned, approach a General surgeon
for his opinion.
Hope this information is helpful. Good day