Welcome back to the Forum. While getting checked for STDs following an exposure of this sort is certainly reasonable, the risk of any STD is rather low. It is unlikely that your partner had an STD and even if she did, most exposures to infected partners do not lead to infection.. Further, I can assure you that your symptoms are not a reflection of early HIV infection. For starters, your symptoms are non-specific and do not represent the complete set of symptoms which are caused by HIV. More importantly, the symptoms of recently acquire HIV do not begin until about two weeks are the infection is acquired. Early HIV would not cause symptoms just 3 days after infection.
My advice would be for you to go on and get tested for common STDs such as gonorrhea and chlamydial infection. You can be tested for them at this time and the results will be reliable. In the future, for your peace of min, you may wish to get checked for HIV too although the risk of infection is rather low.
I hope these comments are helpful. EWH