I get some form of this question fairly often. 99% of the time it's not the saddle, it's the fact that you're not moving around enough because you're not forced to move around at all. Assuming you have the correct saddle for your anatomy, which it sounds like since you can ride just fine outdoors, chances are that trying to find a different one could end up making things worse.

So try to stand more and shift around more before considering a new saddle.