Thanks for your query.Based on what you have described it appears that you have UTI Since you have consulted urologist
who has prescribed you Tab Tomsulosin 0.4 mg once in a day.This drug relaxes the bladder neck muscles During ejaculation bladder neck gets closed and semen enters in the urethra
However as the bladder neck gets relaxed after taking Tomsulosin, semen instead of entering in urethra enters in bladder what is called as retrograde ejaculation
and that is the reason your semen is not coming from penis. This will resolve once you stop taking Tomsulosin.You can stop taking Tomsulosin .
I shall advise you to take some antibiotic like Ciprofloxacin
along with urinary antispasmodics like Flavoxate
or Oxybutinine once a day for 10 days Please get prescription of these drugs from your family Physician..
Do not worry you should be al right in 10 days.