Sounds like Roseola. Typically you get a high fever for about 3-5 days, then when it breaks, you have a pink "lacey" rash all over the body, but mostly on the trunk. I hope your babe feels better soon. Dd had it this year, and she was miserable. They also usually have a huge boost of immunity after, which is great.
Roseola isn't dangerous.
ETA: the rash usually isn't itchy, and disappears after 2 days.