why do I get this???????

Hi, Ebarnes,

Love your avatar, relaxing with your good-buddy there!

I sure can't say what's up with your rash, but a couple of things come to mind to think about. First, lymphedema is an inflammatory condition, and sometimes that can cause a pink cast under the skin, though usually that happens with breast lymedema rather than on the arm.

The other possibility is cellulitis, which can sometimes "brew" for a while before it breaks out into a full-fledged raging stupid infection. So do keep a close eye on this and get help at once if you have any indication of infection. Here's information about it so you know what to look for:
http://www.stepup-speakout.org/Emergencies_and_Medical_Care_lymphedema.htm

You mention wearing a sleeve but not a glove or gauntlet (fingerless glove), so I also wanted to share this short article about the importance of hand protection when wearing a sleeve:
http://lymphedivas.com/lymphedema/gauntletandsleeve/

Be well, and do let us know what you discover,
Binney