Woke up with sometimes painful square rash

[Muchew]

About 3 days ago I woke up with this oddly symmetrical square shaped rash.  It is located on the underside of my knee.  If I don't move my leg I don't notice it, but when it brushed against things it stings slightly.

It started as just a red rash, but now its getting darker red areas on the inside.  I thought maybe a spider bite, but I can't seem to find any similar information online.

[IMG]http://img.photobucket.com/albums/v706/Muchew/CIMG4970.jpg[/IMG]

If that doesn't work, go to my photobucket picture.  I tried to take a picture of it.
http://img.photobucket.com/albums/v706/Muchew/CIMG4970.jpg

Thanks for the help,
Matt

[Ellelouise0063]

I too found an almost complete quare rash on my leg today. It's actually half of a square looking at it side ways. I woke up fine today; cut a lemon squeezed the juice into my water and tossed the peel then ate a salad with vinegarrette dressing that I forgot to wash out it was probably about two or three months old. I also don't think I washed the lemon that well but would it matter since I didn't put the peel in? Anyways right after taking a few bites if the salad I noticed it tasted funky and tossed it then after one drink of water I ran to the bathroom to puke. My mouth started watering uncontrollably. I keep getting light headed and nauseas then throwing up. Do you think maybe I need to take antibiotics? I have cephalexin in my medicine cabbinet that I two months old?? Please help

[Bhupinder Kaur, MD]

Hello,
I cannot confirm anything without examination but it can be frictional lichenoid dermatitis, granuloma annulare or psoriatic patches. Psoriasis is a long-term (chronic) skin problem that causes skin cells to grow too quickly, resulting in thick, white, silvery, or red patches of skin.

I suggest you to get an examination done from a dermatologist and get the diagnosis confirmed as treatment is diagnosis specific.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.