Ladies only please?

I'm 31. My son is now 5 months and I am starting to get my period again. This is my second one and it is on perfect clockwork, however, I have never experienced cramps before and these are absolutely horrible, I can't even stand up straight. After my first son when my periods returned it was never like this. Has anyone else experienced this? Is this normal to have cramps so bad? A heating pad and a Tylonel 3 didn't even help.