Good Day! If you consulted on my clinic with your problem. I would request doing a urinalysis, semen analysis and ultrasound of the bladder, prostate and scrotal area. I would also check for inflammation of the testes and spermatic cord. The most common cause of pain on ejaculation would be infection. Infection will be proven once the results of the above mentioned exams are available. Treatment usually consists of empirical antibiotic. (e.g. Ciprofloxacin). Antibiotics are prescription medications and you need to consult your local physician to acquire a prescription. IN the meantime, I would drink plenty of fluids, abstain from any sexual or ejaculatory activities and drink ascorbic acid everyday. Best wishes to your health.