The missed periods can be due to various causes like stress, emotions, genital infections, hormonal
, thyroid abnormality etc.
Sometimes the pregnancy test can also be false negative in the early cases especially during early pregnancy and in that case the test should be repeated after a week.
YOu may have the repeat serum hcg test after a week to rule out pregnancy and if that comes negative then have other blood test
to know the underlying cause.
Since you are also having foul smell vaginal discharge
so the chances of genital infection causing such delayed period is likely to be the reason in your case.The vaginal smear examination will help in evaluating the cause.The oral antibiotics
may be needed to control the genital infection.You should consult the doctor for the same.
The other causes should also be ruled out.