What Causes Severe Pain In Abdomen And Back Plus Light Spotting?

I took 2 different pregnancy tests clear blue was positive e.p.t.positive but not as bright as the second line.I started My Period but I'm not sure what is going on.I first put a pad on at 7 a.m. at 5 p.m. I usedthe bathroom when I wiped there was dark read almost gritty on the toilet tissue and pad, I wore the pad most of the day and there wasn't even enough to have to change to another one I did anyway just to see it slowed got heavier. I went to the bathroom at 8 p.m. on the pad it was dark red again gritty on the pad also when I wiped very greedy as well ,not that much on the pad I use a q-tip and inserted it ,when I observed the q-tip it had a type of tissue like matter .I had a miscarriage in October in 2014 which started in the same way .I am 34 years old have had my menstrual since I was 8 years old, I have 3 children17 years old 11 years old and 7 years old .I know what my normal. It is I know what it is to have a normal period also what it is to have a miscarriage ,I am having severe pain directly in the middle of my lower abdomenI cannot deal with the pain it is very very painful also my back hurts in the middle lower area . I am just using a panty liner at this moment because its not a lot of discharge of blood .I would like to know what might be going on what could be going on ,and what this could be . Thank You, Heidi E. In pain need advice before going to a Dr. Or E.R