Still worrying!!!!

I hope some expert/doctors here can give me some advice to lessen my worries,I am guy working here in cambodia..I had unprotected sex with a sex worker here in Cambodia last Aug.9,2010,I did not use condom but after penetrating 2x into her v######, I hasty pull out my penis and I went to toilet to masturbate to ejaculate,3 days after I got flu and cough and the flu last 3 days but my dry cough continuous for more than 1 month,and also I notice that I have like a rash in my right shoulder,it looks small pimples with brown color,.I got HIV test by ELISA Test to the following date..
1st Test.Sept. 18,2010 (5.7 weeks after the encounter)- Result Negative
2nd Test.Nov 1,2010 (exactly 12 weeks later) - Result Negative
3rd Test.December 17,2010 (4 moths & 2 weeks later) - Result Negative

As this date the symptoms I notice to my self,I feel burning sensation to my both feet and knees for almost a month until today,and I can see a swollen nodes/gland in my right armpit it's almost 1 month also..
My question is can I considered that the 3 HIV test I did were conclusive and considered my self that I don’t have HIV.. how accurate is the ELISA test?thanks for your responses in advance..GOD BLESS