Hello,
I cannot confirm anything without examination but it can be a thrombosed penile vein, or a plaque associated with Peyronie’s disease, a sebaceous cyst or Mondor’s disease(less likely). I suggest you to consult a urologist and get it examined.
In Mondor’s disease, there’s inflammation of the superficial veins of the penis and one of the commonest causes of the same is vigorous sexual activity. Abstinence from sexual activity is important.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.