a rash on blothches on chest, stomach and back

I have a definite pattern of blotches on my chest, stomach and back, on the back, two are round and the rest are oval, up and down, resembling ribs.  On the stomach and chest, the blotches are more oval, side to side.  They are not raised or itchy, just a redness that has existed now for three days.
I always wear a shirt outside and two undershirts at the gym, for weight training or cardio.
I also do not see any tick bites.  It is the pattern of the blothches on my back that concern me.
Could it be a contact dermatitis, from sweating, and changing shirts before I showered that had been washed in bleach?  It is impossible to see a doctor on the weekend, except at an emergency room, where there are no dermatologists anyway.  I wish that I could post a picture which could accurately show the condition on my back.  Digital photography shows the patterns and the coloration.

[Alan Rockoff, MD]

I'm guessing that you're a young man.  The most likely diagnosis would be tinea versicolor, a superficial, noncontagious fungus that produces blotches like the ones you describe.  You can try applying Selsun Blue (1%, over-the-counter) overnight and washed off in the morning for 7 days.  Then let the color even out by itself, which it will over time.  You should see a doctor at some point about this, since it often recurs and you'll need a general approach to deal with these recurrecnes.

Best.

Dr. Rockoff