chronic diareah ? or AIDS?

Hello,

       Im a 20 year old male who has had chronic diareah the past three months ever since i traveled abroad to Australia from New York. I was fine until i went into one of my health classes in the first weeks and the instructor said some people who are diagnosed with AIDS have a syptom (symptom) of Chronic DIareah. Ever since that day i have been stressed out, i do drink a lot probably average week here i get drunk 4 nights out of the week. I usually had diareah following the morning of a heavy drinking night but now even two days after drinkin i still have it i son tknow if its due to stress from that day and from being a long way of home or not. I am going to get tested as soon as i get back but i want to see other peoples ideas of what could it be because i dont do drugs and i have had sex without a condom a couple times but never got anything and find it very wierd that the person would only have AIDS and no other STD. I dont know iam very streesed out and would love to see someone elses ideas please help thanks.