See a doctor!
It sounds as if you had a miscarriage, if you are still having symptoms see your doctor. It is also possible you have a sexually tranmitted disease. Other things are possible but these are the two most likely.
Yes it is. Our bodies change every 7 years and much of it is hormonal. Sometimes stress may be the cause of it. The only time you should worry about it is if you miss too many periods or you are having too many periods, bad cramping (if you usually don't have it) then see a doctor. The birth control pill/patch can also cause this.
Stable Periods of little change interrupted by brief periods of more change is known as punctuated equilibrium.
yesterday
Paragard may change the flow, cramping, or duration of bleeding but not the timing of bleeding.
Evolution.
Evolution of man.
punctuated equilibrium
Nothing serious, periods change all the time and isn't anything to worry about, but if you need your mind to be put at rest make a routine appointment with your doctor just to put your mind at ease.
Evolution
it change by the age..
No