So my last menstrual was December 10 and it lasted 4 days light its now January 5, and I spotted 5 days ago ?

Best way to check is to do a hone pregnancy test. I currently am 35wks pregnant and I spotted very lightly around the time I would norm get my period for my first 2months. If you take a test and it cones back negative but have other signs of pregnancy like smells bothering you tender breasts nausea that kind of thing call your OB they can do a blood test to check for pregnancy. If you are on because you may want to check side effects some pills cause you to have light spotting to no bleeding certain months. So do a home test and if your still unsure call OB.