The weight gain can be attributed to the the use of contraceptive
pills, which is quite commonly seen. But the worrying aspect of your query is the continuous bleed and foul smell.
If you were experiencing only a bleed (mild) with a history of hormonal
imbalance, your doctors would have to look into a possible imbalance being the cause again, but with the presence of a foul smell, other conditions like infections, fibroids, endometrial abnormalities, polyps, etc; will also have to be considered.
Please get a transvaginal ultrasound
scan, hormone level check, pap smear
, bimanual examination and urine analysis conducted to find the cause for the same. Also request for a check on your hemoglobin
levels to treat suspected anemia thay could have resulted from the blood loss.
Hope this helps.