The answer is no.
The STDs like gonorrhea ,chlamydia, herpes affect your genitals (vagina)---discharge, blisters, burning, pain etc.
HIV, hepatitis may cause fever but, their presentation may take upto 4-6 wks.
Your symptoms are more suggestive of common viral infection ('flu').
Yes, pregnancy is possible, if you had unprotected sex.
Otherwise, it may just be part of your period, a normal variation.
Then i think---these symptoms are due to the morning after pills.
Your chances of pregnancy is very unlikely.
Please relax.
Doctor
MD