Headache, Non-tender Lymph Nodes After Having Unprotected Intercourse. Worried About STD?

hi doc.this Patrick from Kenya. am a worried man after what happened 31 days ago.i penetrated a ladie whom i came to learn later she was reactive.the penetration lasted for about 30 seconds before i went on for protection.have been on pep which i started at the 71 hour.1.what are my chances of contracting the disease 2.what r the chances that the pep i took will work since i took it almost at the last hour?3.i carried out a determine test on the 30th day it came out negative 4.i have some mild headache and some non tender lyphnodes.could they be as a result of stress and anxiety?
thank you;