Is a 6mm epididymis simple cyst concerning?

There may be several reasons for this. It could be caused by infections like urinary tract infections or sexually transmitted infections. Sometimes, it might be the result of inflammation or even an injury. They might examine you and do some tests if needed to find out what's going wrong and give you the right treatment for you. Meanwhile, it would be better if you refrained from any physical activities that aggravate the pain, such as masturbation, so that the body can heal itself properly.

It requires immediate visitation to a urologist. The cause of the disease may be injury, infection or testicular cancer. This underlying cause needs to be diagnosed by a medical practitioner 

Since you are worried, it is suggested that urologist should be consulted for a detailed diagnosis and treatment plan. It could also be a birth defect, hormonal dissonance or some other medical comorbidity that causes the condition. Thus, one should consult a specialist in the field.

All too often individuals complain about the pain that is located in the lower region of a penis as a result of masturbation. If the procedure is too hard or if there is a lack of lubrication, pain is likely to develop. But, you said discomfort is usually around a 2 out of 10. To get over it, you can have a time out for a few days without masturbating, doing gentle strokes on the skin with lube, and ensuring appropriate lubrication the next time.