I second, third and fourth the idea to buy bike shorts. I felt a lot like you do when I started. Someone (possibly Donheff) here made that recommendation to me.
Depending on your undergarments of choice and pants, your bottom end could be, being chaffed by the seams in your clothing and the seat.
The remedy is to go out and a good pair of cycling shorts/pants with the good chamois, you'll know which ones by how the seams are recessed in the padding. They are not cheap but you posterior will thank you.
You could try angling the nose of your seat down just a touch too. BTW I swapped out my seat when I bought my bike...maybe your seat geometry isn't good for your sensitive areas.