my rash started on upper right arm. it started with a little circle of dots and 2 weeks later it is spreading down to elbow in red lille hard dots or bumps that itch. some of them go in dotted line and some go in half o circle but there kind of hard and clumped together. they can itch at times very bad unless I take benadryl. there is no puss or scabs. I had this last year and it spread slowly and dermatologist took biopsys and all kinds of test and couldnt figure out. it went away about 2 months later. I just cant figure it out. it doesnt look like any of these rashes i have been looking up. any ideas?