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Your risk was low and you must have been tested on 4th generation of HIV test since it is most widely used as a standard test in diagnostic centers across the globe. I am confident that you already know at 4 week a IV Generation is conclusive for you.
Supposing that you tested with a III generation, the result would still be very reliable at 4 weeks, since most people would already test positive if they were to be infected from their exposure. It won't be a bad idea to take a final test at 6 weeks for your own peace of mind.
Your symptoms seems unspecific to HIV ARS, they don't show up so late, as stated before, your risk was low and a negative at 4 weeks only reflects that you are fine. Just get that final one at 6 weeks, I foresee a negative.