37yrold.have single small red spot on penis head since a week.doc has asked me to wait for a week.but it is not increasing or paining or itching.last sex 2 weeks ago.i am really worried.is it something serious?

Perhaps your doctor is concerned about syphilis and waiting to see if it will ulcerate to become a typical syphilitic chancre, and/or to do a blood test. It's too soon to otherwise know the cause; no test detects syphilis this soon. There is no harm in waiting, but you must not have sex with anyone before you return to the doctor. Also, hands off: do not poke, prod, or squeeze it. Good luck.

From your description does not seem serious unless your sex was with a sex worker or stranger. See your doc.