Thanks for the query to H.C.M. Forum.
Previously it was normal period & again bleeding i.e.loss of blood .
As there was loss of blood so naturally you were weak.
After drink you vomited and this causes further loss of fluid from body.
All these thing causes depletion of fluid from body i.e dehydration
Due to dehydration you are feeling weak and loss of energy from body.
Since your husband already operated for sterilization
so chances of pregnancy
not at all.
This is the first time of bleeding so may be normal due to tension ,stress , so need not to worry.
If reoccurs ( bleeding) then consult a gynaecologist and get his opinion and ultrasound
of uterus and genitals .
plenty of fluid & water ( added with salt & sugar) sip by sip will help you.Still not under control then take intravenous infusion from a doctor.