i've been having cramps (2 nights ago it was really painful), nausea, hot flushes, headache, lower back pain, abdominal pain, sensitive breast for two weeks now. had an unprotected sex last jan 5. my last period was dec 23. i had my period twice last december, on the 10-16th and 23-29th. today is my 2nd day of missed period. i had a home pregnancy test yesterday but it was negative. any idea? i need to know if i'm pregnant so i could have measles vaccine because there's measles outbreak here now. thanks.