Breakthrough bleeding after heavy lifting?

I am 31 years old and have regular periods. They are heavy though. But between periods when I lift a heavy object, say a computer, or stretch the wrong way I get breakthrough bleeding. It doesn't last long at all. Its bright red and really doesn't look like period bleeding. Is this common? Has anyone else experienced this? I am very concerned it might be a cyst on my ovary or something worse. Thank you for your time.