Hi, 48 Yr Old Healthy Male. On Friday Night I

Hi, 48 yr old healthy male. On Friday night I had some itching on the inside of my thigh. It continued into Saturday and Saturday afternoon I took a shower and noticed there was a spot that was red. By Sunday morning it was a large bruise about the size of my fist. Purple and red around the outside, a little red to normal color in the middle.A bit sore to the touch. The color has changed a bit over the past couple of days. Lightening in some spots and darkening in others. this all happened while on an RV and golf trip, sleeping in a rented RV trailer. I was originally thinking some sort of insect bite. Any idea?