Progesterone question

by Sarita
(India)

I have done pregnancy test (2 days after i missed my periods) at home and it came positive. So i went in for a check up , there the doctor couldn't see the baby in the machine and later, she wrote a prescription of Susten-200 (soft gelatin capsule) twice daily along with Cap Foliaine once daily.

I came home with the medicine and had it after my meal, (as doctor's advised - i may feel giddiness so it can be taken vaginally then) I slept for an hour or so and then after i woke, i worked around the house for an hour, then the giddiness came on very strongly and it kept on for 1/2 hour!!!.

What i don't understand is:-
1) Without checking the score for a need of progesterone, why was i prescribed the medication?
2) Without the history of miscarriage, why was i prescribed the medication?
3) I am already a mother of 1 normal , healthy child and was not prescribed susten-200 that time so i was confused this time about the medicine so i googled susten-200 and came onto your web and I checked your test for progesterone and my score is "4.5"!!!???