Miscarriage or implantation bleeding ?

I got positive tests this past weekend. Yesterday I started bleeding. I woke up to bleeding on my bed. It’s bright/dark red and some small clots. Cramping a lot especially in my back and lower belly. I’ve been waking up with the worst headaches ever as well. I’m also very gassy in the stomach (bloated) and have been have some diarrhoea… is this an early miscarriage? Would I get a positive test before implantation bleeding? I’ve never had this with my other children.