I would say that it is more of the after bleed.  It does stop and start and get heavier and lighter.  I'm going through it too, and I have noticed that I seem to only bleed at night, and that it is very heavy.

It can take upto 2 months for the post natal bleeding to stop, at least that's how long I bleed for and I've been told it is normal.

It is possible that your body is trying to ovulate though.  This can happen any time from the birth of your baby, but it isn't considered to be a viable egg because it is usually rushed out of the ovaries and can be rather painful.

Treat it as you would your normal period though, that is heat packs, painkillers etc etc etc.  Us women have it so tough compared to the men, but then again, the men have to put up with us!