I had sexual contact with a girl for about 1 year and six months ago. I used a condom but lately i've been experiencing symptoms like frequent headaches, itchiness under the armpits, stifness of neck (but not swollen) and forgetfullness. I sometimes fear that these may be symptoms already of HIV. But results on the ELISA test a year after the contact showed negative results. I am planning to donate blood again to check under the ELISA test whether I am HIV-positive. Please advise. Thank you very much.