A sed rate is used to monitor inflammation in the body.  They measure how far from the top of the test tube your red blood cells within and hour.  The more inflammation the further and faster you RBC's fall.  Normal is 0-15 (or 20 for women).  So basically your sed rate changes as flares and infection in the body changes.  If your stress triggered a flare or inflammation somewhere in your body, then poof the sed rate goes up. It can change for the good or bad rapidly. Doctors don't like to see an elevated sed rate for an extended period of time.  And will usually react with scripts for DMARDS (plaquenil, mtx, arava, etc.) Medication like high doses of prednisone will also affect your sed right and white blood cell count. 

I have an old medical journal in my library that has a case study in which sed rates of people with different condition (RA, Osteo, Lupus, Heart disease, Cancers) is taken every 10 days for 4 months.  The sed rates jump all over.  As the the conditions were treated, the sed rates calmed down.  This was a case study back in the 40's used to qualify sed rate as a medically necessary procedure used for monitoring of any condition.

Blah blah blah.  I know. Sorry