According to the data you provided, you might be experiencing genital infection. The blood might originate from the testicles or from the prostate. Depending on the organ that is affected, you might have orchitis or prostatitis.
You might want to visit your doctor for sperm culture that would tell the exact bacterial cause and the most effective treatment.
However, if the blood appeared only shortly after the spermatocele was removed, then it might have appeared because the tissue was not healed completely.