OK. I Periodically Have What Look Like Bite Marks To

OK. I periodically have what look like bite marks to appear on my toes, arms sometimes my wrist. About a month ago I was taking a weight loss med. Can't remember the name, I think it was aphenthemine (sp?).
I had to stop taking it because it caused my heart to rise so high I was afraid of a stroke .
it caused me to drink plenty of water. After I stopped I tried to continue the water intake to try to flush it out of my system. But occasionally, I still have the red rash or bite looking marks to appear.