I don't understand why I'm bleeding so much

I was told that having surgery could change a menstrual cycle, it seems like it did.

A week before surgery I had my period. 2 weeks later I had one again, it was less than the usual amount of time.

Had one that ended prior to this past weekend, and now I'm bleeding yet again.

Is this a cause for alarm?

I would suggest that you discuss it with a gynecologist. Good luck!