Could Sore Breast And Nausea Be Due To PMS Or Pregnancy?

hi, ive have had a child three years ago, but im very confused to where i could be pregnant or not. I currently have my periods (or what i think is my period) as i cant tell the difference between spotting or implantation and periods, i do how ever seem to be having pregnancy symptoms (biggest one is nausea from 07:00am onwards) i have always been one that preffers salt over sweet, but for the last week only wanting to eat things like donusts and chockies, and want to get sick at the smell of raw meat?? my breasts are sensitive and swolen, hardish (left alot more than right) could it be that im pregnant or could periods cause these symptoms?