+1 to what BleeckerStGirl said.
I ride on unpadded wide Brooks B67 saddles. The same as BSG's, only mine have springs under them.
If I ride a regular women's saddle (like the Selle Italia lady gel flow) it is narrower than my sit bones and I end up with my pelvis meeting the saddle at the rami (the "A" in BSG's pic) rather than on the tuberosities (the "B"). And then I have pain just like you describe.
Measure your sit bones, then select a saddle or two that are wide enough to support your sit bones. Be sure to buy them from someplace that will give you a return if the saddles don't fit!
Wallingford Bicycle Parts has a great 6 months return period. They pretty much only sell Brooks saddles, though. www.wallbike.com
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson