Thank you for your query at DoctorSpring.com
There is nothing to be worried about. You don't have any symptoms to suggest that you should be worried.
The urethral opening can be looking distended secondary to some infection or trauma or may be the normal appearance for you.
Regarding the cyst or diverticulum, a lot of patients may not have any symptoms but majority shall have some urinary symptoms such as poor urinary stream, straining, intermittency, dysuria.
You don't have any of the symptoms and your chances of having cyst or urethral diverticulum or any other pathology is very minimal. Your swelling should settle down by itself over next one to two weeks with the help of anti-inflammatory medications.
Nothing to be worried about. Stay reassured.
Hope this was helpful,