Missing a period or 2

Hi,
I believe i've been missing my period for the last 2 months. I dont remember getting one in december and january is almost passed so I am sort of freaking out. I dont know what is wrong with me. I took two home pregnancy tests and I know that i'm not pregnant theres no possible way I am. I have been getting light cramps in my lower abdomen ranging about a 2 on a scale of 1-10 in pain. I had a cold that started in mid december and have been really stressed out with my job lately. So my question's if it is or is not possible to have skipped two periods from stress and a upper respiratory's medications such as mucinex. I just want to be sure this is something minor. I read on the internet about polycystic ovarian disease and dont have coverage just yet. I'm really scared please help.