Oooh! Are you sure about scrubbing with that soap!? I have a feeling your sensitive skin probably can't cope with it, especially with the scrubbing... Mine can't handle anything apart from Dermalogica, LUSH and my lovely Au Thermale Avene spray!
Anyway, chances are, all the scrubbing is making that soap of yours penetrate deeper than usual. If your cleanser is completely compatible with your sensitive skin, and gives you enough moisture, then this is good news, but if its too harsh, its probably drying you out even more, causing your skin to create more oil to compensate. Scrubbing is only good when your cleanser isn't going to cause damage, as every time you scrub, you're giving it a chance to go deeper! If you want, you could try switching to a nice, gentle liquid, clay or buttery cleanser, I guarantee you there's nothing better! [The only cleansers that seem to agree with me LUSH's Ultrabland, Baby Face and Angels on Bare Skin, or any of Dermalogica's] I've had the works: acne, flushes, oiliness, blackheads, excema, hives...And everything in bar form is just too much for me!
Another thing about scrubbing, is it can uncover under the surface blemishes. A buildup of dead skin cells can actually cover some blackheads, but scrubbing gently actually helps your cleanser get rid of them. Once again, finding the best products possible for your skin is essential.
The redness afterwards is caused by increased circulation, due to the warm water and massaging. If this doesn't recede, hold something cool against your skin for a while, or don't scrub as hard, or for extended periods of time. Exercise also helps!
I also agree with the Dermalogica Precleanse recommendation. This product is fantastic: its soothing, and makes cleansing all that more effective!