Welcome to HCM.
You had your HIV test
done how many days after the risky contact? What type of test you had?
There is every possibility that one can remain negative for HIV even after regular contacts for a very long period. We have seen many such cases in married couple. They are called as Sero-discordant couple.
All your symptoms can occur to any body and may be not related to HIV.
Consult your physician and get checked once again under his/her guidance.
Get well soon.