Wah, I can sense you're worried lah, especially with your ectopic history, yang tu memang boleh buat kita paranoid sikit kan. Back pain awal pregnancy tu memang boleh terjadi, tapi the fact that your period was unusual (short cycle, short duration) and now you're getting night nausea plus the back pain, honestly kena go see your doctor ASAP la, sebab dia kena confirm dulu whether it's pregnancy dan more importantly, rule out anything ectopic lagi. Jangan worry sangat first, tapi don't delay either, a few of us have been through scares and honestly early scan je boleh tenangkan hati. Do a pregnancy test kalau belum, then book your GP atau klinik to get checked properly okay?