Miscarriage or just Af

Ok so I don’t want to sound crazy but I just need advice me and my husband are trying to conceive so this month we tried and my periods have been regular and for some reason this month I was 3 days late I tested negative for pregnancy but then I started spotting for 2 days light brown then all of a sudden I was bleeding so heavy with huge clots sorry tmi and it lasted all day I had pains in my lower back and stomach mind u it was hurting even when I was spotting I don’t know i never had bleeding that heavy ever I’m just lost like what is going on. Any advice