10 PTZ! Periods? I think i did something wrong?

Hey guys, So im 15 and recently did something stupid like the atkins diet which im not allowed to do at my age.... well i lost 5 pounds and gained it back quickly, as i wasn't able to follow through. I did this about a month ago, maybe had one period in between and i am one one now. I am getting horrible cramps/ pains that seem to have worsen within that time. I usually take pamprin, but now that is not even working and i can't take midol. Do you think the diet is effecting my periods? My periods have gotten a lot lighter, but the pains are worse sometimes unbearable. Right now the pains are light but i feel really sick, i usually smell blood and get nauces too. What did i do?? and no i am not ually active.