PLEASE NEED ADVICE.. sad.. period was suppose to start today... faint positive yesterday: negative digital today... symptoms

Last week I was having backache like my period was coming and no period. Today I am having bad back aches like my period is on it's way as well as constipation... I can't use the restroom at all. Only other symptom is increased hunger (my belly growls a lot) and headaches as well as exhaustion. Af was due 3/1 to 3/4 (today). Any ideas??? Please help