I used to have this problem back in the day when cut-out saddles were not available. Once I switched, the problem went away. I've briefly tried non-cutout saddles now and then, but I always end up with chafing in this same area. It stings to pee or wash when I ride a saddle without a cut-out for rides of more than short distances.
Good luck finding a saddle that works for you!
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow