It could be that the saddle has changed, sagging in some way, or was never quite right, or that your body has indeed changed. When I get this I adjust the saddle angle to move the nose down just a tiny bit to reduce perineal pressure in favor of more support by the sit bones. If I then start sliding forward I try to raise the nose a tinier bit. You might also want to look at a saddle with a cutout. I think the Specialized Alias and Toupe provide good solutions of this sort. In these saddles you have to get the correct width. The Specialized dealer can help you find the correct width.

You might want to get a Thomson seatpost (probably a setback), which is one of the ones that allows you to do this kind of micro adjustment.

Then write down all the measurements. If you can be accurate to the millimeter it would not hurt.