Cramps in abdomen. Getting vaccines fro Hep B, cholera. Taking doxycycline. Suggest?

Hi, I ve been getting lots of vaccines lately to name a few - hepatitis b , rabies , cholera , Japanese Ens. I m also, taking doxycycline 100mg a day (so far for only 3days) - all this because I m travelling to India soon. However, my period is late by 3 days - I took a pregnancy test which was negative but I m wondering if all this medication I have been taking is causing it to be delayed? Is that possible.. also, I never felt the normal cramping before my period was due like I usually do and my lower back is starting to feel like its compressed or something?