I don't know why you're itching, but I don't think it's a side-effect. I'd wait a couple of days, and call then if necessary.
I have a similar problem of white bumps that developed on my arm over the last week; however, mine are smaller, and I haven't taken any medication. The bumps look like small mosquito bites or pimples clustered together around a dark red rash that developed after I scratched the initial two small bumps. After I scratched the bumps, some clear white substance came out followed by a little bit of blood. Over the last week, a red uneven rash developed around the 2 initial bumps, and more bumps appeared at its edges. Other than being a little itchy, the rash does not bother me. The area is cool, and does not smell. It is a little sticky around the edges, and looks like a burn. It grew from 1x1cm to almost 3x3cm in 1 week.
Thanks in advance for your help!
My rask is similar to Linta's but mine is spreading everywhere. It doesn't bother me other than the itch, and when I sweat it burns. My doctor perscribed Zyrtec and Doxycycl HYC, which are not working. Looking foreward to your help