I'm pretty sure you'll find it's excess pressure and angle. Why you need to use such pressure and angle is usually caused by a slightly dull edge or as someone mentioned a rolled edge though I'm not convinced the latter is all that common. I would normally take a razor that is just starting to dull and give it about 50 laps on a chromium oxide pasted paddle strop, then strop normally and shave again. If you have a linen strop, you might want to up the number of laps on that before the next shave... 50 or more if the edge isn't popping hairs and meeting the other normal indicators of being completely sharp.

By the way, you have a great product to use after a rough shave in your arsenal, but it doesn't sound like you are using it that way. The Proraso Pre-Post cream is my favorite "I think this shave went badly" after shave product. After rinsing and cooling off my face with some cold water, I just use a small amount of the prepost and rub it in... too much will leave your face looking like you've used mime makeup and don't get your alum block near it... alum makes prepost curdle.

Yupp, tweak that edge, back off the pressure (should still cut nice and close if it's sharp) and a schmear of prepost diluted with the moisture on your face to finish should calm things right down.

Regards

Christian