it's not scabies- they itch and are usually only in creases/folds like fingers and groin area.
it's not chicken pox- it's not crusting, weeping, "dew drop" appearing lesions
your doctor should've asked you all these questions and probably more (aside from being able to see half of them)
when did you notice it start, does it itch at all?
it started centrally and moved outward, correct?
are they all red? or skin color, or what?
are they better in the sun? or found under your shirt more than not?
-you mentioned no change in laundry detergent, soap, etc., what about foods, activities, etc.?
is any of it raised up a bit? or is it confluent on your skin (kinda like birth marks, in that they're just color changes)
are they circular, blotchy, etc.- what's the shape?
are they all the same in appearance?
have you done anything to make it better? worse?
any pain?
other systemic side effects- headache is one, and your eyes hurt? is your vision the same?
runny nose, cough, sore throat, have you previously been sick? does your neck hurt? how are your muscles and joints?
any family history of rashes, diseases, etc.
taken any medications recently? allergic to anything?