<s>[INST] I have a cyst on my left epididymis that is around 3cm.  I have a dull ache there most of the time and cannot do things like riding a bike without extreme pain that radiates to my abdomen.  However, every 6-12 months after having lots of sex (wife, no STD) the pain gets worse and i feel nauseous all the time.  Is this caused by an infection in the cyst? [/INST] Hi welcome to Chat Doctor forum.  Thanks for asking a question to Chat Doctor. F.  You had a cyst on the epididymis of around 3 cm size. It has continuous dull pain, especially in movement. Pain is horrible and vomiting feeling after sex.  The cyst appears to be attached to the epididymis, and the pull is felt up to the abdomen through the cord. Sex is expected to be vigorous, so it shows more pull and nausea.  As it appears to be fixed, better consult a surgeon for diagnosis and treatment. You may need to have surgery for pain relief.  Wishing for a quick and complete recovery.  Best regards. </s>