Two days ago, i went for a blood test. today, i went to my doctor office to discuss about my obsessive fear about hiv. however, the nurse put her stethoscope right on top where blood was draw site. am i at risk of hiv infection? very scare?

You are at no risk of HIV from what you described. Your phobia of HIV may require consultation with a psychiatrist. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs.

What you are describing is not a path for infection. One of the safest places to be is a doctor's office because of Universal Precautions. Please talk to your General Practitioner about your concerns. Care provided by a mental health professional, to help you address your "obsessive fear" is indicated.