I developed a red, itchy rash one one of my thighs. It spread to the top of my hips by the next day. I don t know where it came from. It just suddenly appeared Monday evening. I looked online but don t see any pictures that look like it. I went to a doctor, and she said it is come kind of rash, that it might spread some more, but she didn t indicate how long it might last, what to look for before getting concerned. I m taking an antihistamine and am putting on a topical cream, but the rash is getting worse I think, itchier even. Should I seek a second opinion, or do allergic reactions tend to happen like this? I can t think of anything that one leg was exposed to that the other one was not, in terms of allergies.