No period for like 3(??) months, then about 2 weeks after I finally I got one, I'm having intense cramps with no blood yet

What does this mean? What could this possibly mean?

I'm very unhealthy and my body sort of just does stuff, so it's likely the entire answer is just "It's stress induced and there's nothing you can do about it", but maybe there's something going on here that I should be concerned about?