Bike Pain

by default biking on the trainer is going to be a lot harder on those sensitive areas. There is just less shifting of position and it's a lot harder. I would suggest you get a fit if it doesn't feel comfortable. Although it did take me several months to get fully comfortable and I did get a few 3+hr trainer rides in this winter.

Make sure you are taking time to get out of the saddle and relieve some pressure. I bought a Kurt kinetic rock n roll trainer that helped as it allows some lateral motion similar to riding outside.

If you decide you need a fit adjustment, here is a map of fitters that may assist you:
https://www.slowtwitch.com/fitters/