Red itchy spots on shins, elbows, behind knees & neck. No one else in home is afflicted. What is it and how do I get rid of it?

Jock itch. See your physician to get checked for accurate diagnosis.My guess is tinea corporis which is a fungal infection of the skin .It causes an itchy, red, often ring-shaped rash in these warm, moist areas of your body. It is common in people who sweat a lot, as do athletes. It usually respond to topical anti fungals creams.