Period cramping vs pregnancy cramping? other symptoms of pregnancy?

I've been told that you can have somthing like cramping in the beginning of your pregnancy. I was curious how close it is to slight period cramps. I'm due to start my period today and i have slight cramping, but it isnt much. I normally would even think to much about being pregnant possibly, but for the last 3 weeks or so now i have been very tired and i've had nasty headaches, as well as a short 3 day period last month. the main concern at the moment is i love tapioca pudding i had a pudding cup yesterday and it was fine, but i opened one today and it tasted like pepto bismol to me, but when i had someone else try it they said it was fine? so my question is, could my slight cramping be due to a pregnancy and should i take a test or wait it out and see? thanks