Thats normal what happened to you.
I also got those red blotches after the body acne went away.
They can take months or even a year to go away.
I'v always had great success with Doxycycline when it comes to gettting rid of body acne.
The problem is when the red blotches are still there when the acne goes away.

For a body wash.
I recommend the Neutrogena Body Clear Body Scrub.
This has 2 percent Salicylic Acid, Green Tea, Aloe, Chamomilla and is very good for getting rid of redmarks.
Its much better then the Neutrogena Body Clear Body Wash with Salicylic Acid.
The Neutrogena body wash did nothing for me.

When you get out of the shower.
I would then use Paula's Choice Weightless Body Treatment With 2% Beta Hydroxy Acid.
This is a lotion for acne.
Leave it on your body. Dont wash off.
This is very good product for getting rid of marks on your body when the acne goes down.
It has alot of good incredients.
2% Salicylic Acid, 2% Beta Hydroxy Acid, Green Tea, Flower Extract, Vitamin A, C, E, Grape Seed, Selenium, Willow Herb, Magnesium, Zinc Oxide.