Hi, Veltam is known to cause retrograde ejaculation meaning your semen will go back into bladder at the time of emission. This is entirely harmless and reversible, and this does not interfere with the quality of orgasm. I suggest you continue using Veltam till your stone gets expelled, because this is indeed a good drug for letting small stones come out of the ureter spontaneously as the other option might be an endoscopic surgery for extraction of stone, which though simple, could be expensive, and at present, avoidable.