Hi Doctor, I Had Sex 10 Days Back And I

Hi doctor, I had sex 10 days back and i was fine and three four days after I master-bated and the very next day i felt burning and since then I have been facing pain in my penis. Got tested negative for chlymadia, gonorrohea. Even the UTI is fine. But my penis pains for no reason. I don't have scars, no discharge nothing. My pain is persistent even the penis is not erected. Generally pain is more when penis is not erected and when i grab/hold my penis i feel comfort. Its at the penile base where the penis comes out of the body. This pain is intermittent but sometimes it stays for longer duration and its really painful. I don't know if i am overthinking but i think my vein is swollen but the physician said its normal. Please suggest.