Unsure

Fr the last few days I've been feeling exhusted, sore boobs, tummy is looking like I'm about 6 months pregnant. Metal taste in my mouth. Ect My period was due today. No pains as such like I normally do. Went to the toilet this morning and a bit of blood was in my knickers. So thought I've come on. I changed and put a pad on however there has been nothing else about from a small amount of darkish blood on pad. Im confused as if it's implantation or period. 

My last period only lasted a a shorter time then normal but. I'm just so knackered. Some one help please ☺