Any info will help us help you, so give us a bit more info.

What kind of bike do you ride? Drop bar, flat bar, etc...?
What kind of shorts are you using and how old are they?
Do you sit up or are you in an aero position?
Are you overweight?

I find that the saddle is rarely the problem and is usually either adjustments, shorts/bibs, body weight, or a combination of them all. If you get one of those problems corrected it can make a huge difference so getting them all corrected lets you ride without even thinking about it. Small adjustments can make a huge difference and sometimes its not the saddle at all. Assuming you're on a drop bar road bike, be sure you have the basics covered. Start with leveling your saddle, then be sure you have the proper leg extension with a slight bend at the knee when at the bottom of the pedal stroke. From there I would start to tweak things a bit trying different adjustments but keeping a log of where you started so you can go back. I had a similar problem not to long ago where I felt good heading out but half way through my ride I felt bunched up down there and found that as I got fatigued I was sliding forward to the nose of the saddle which means my weight was being supported by my junk instead of my sit bones. I corrected this by putting a shorter stem on the bike and tilting my saddle nose up just a hair.