Brief Answer:
The risk of contracting HIV in your case is very less.
Detailed Answer:
Dear XXXXXXX
Welcome to HCM.
You had an exposure 3.5 months before after which you had developed sore throat and multiple cervical lymph nodes but these might be due to some other infection that already subsides with antibiotic therapy. The burning in the groin region is also not significant for HIV becuase single unprotected intercourse with unknown status partner carries very less risk for HIV.
It is more than 3 months after the exposure so you can go for 4th generation HIV Duos test to get 100% conclusive result because the window period for HIV varies from 15 days to 3 months. The negative result will remove your fear and anxiety completely. Further, stay away from such unsafe sexual practices to prevent future risk of HIV and other STDs. If still any query is there feel free to ask me again and I am here to help you out always.
Thank You