Period, headaches, PMT

Hi there,
I used to have the most cruisy periods ever.... until I had my son 16 months ago.
I've only had I think 4 cycles since I had him, initially VERY heavy but the flow is back to normal now. However, my hormones seem to be affected much more than they ever were. I get a headache just before it begins which lasts about 4 days until finished, I also get quite down which is unlike me.
I was going to go to the doctor but I wondered if anyone knew if there was any vitamin or product taken around that time that would help? Especially with the headaches.

Iron is not a bad thought, thanks for that! Don't want to go back on the pill, still BF anyway but it took a year after coming off it for my periods to go back to normal last time.

Thanks for that!