I myself am in a situation where I am worrying about having ars. I got nightsweats/chills for 2 nights immediately upon finding out the possiblity of having hiv. This was most likely due to anxiety or at least this is how I think when im thinking postiively! This burning sensation is not a symptom of ars. Burning or numbness in the hands, is though.
From what ive read, and ive read a lot, seroconversion can take place within a week or so after exposure (wether it was sexual or drug use also has an effect). It sounds like this "low risk encounter" is causing you a lot of worry. These symptoms very well could be due to anxiety. I got a question for you... How often do you check your temp??
Contact me on aim if u'd like, leave a message if im away. Sn name: asudjbliss
-im paranoid like you too.