You probably have too much urethral/soft tissue pressure. You either need a different saddle, or to play with the saddle adjustment to relieve urethral pressure (fore/aft position, angle, etc). Your weight should be supported on your sit bones, not soft tissues. Also, it should go without saying that good hygiene is important, always wear a fresh clean pair of padded cycling shorts, no underwear, and change out of them quickly after riding.