Yes yes if temp stays up you need to test.
Yes I bled fairly heavily for 5 days straight, which is a long and heavy period to me. I didn't even realize I was pregnant (cause who bothers testing when they have AF, amirite??) but then when I went to my first ultrasound there was a full grown baby on the screen instead of a fish and I was like "wow that thing is amazingly well developed" and then the tech was like "I think you got pregnant a little sooner than you thought." About 2 weeks before I got that heavy bleeding, as a matter of fact. And then it turned out I had 2 placentas, one (the babyless one) was unfortunately right on my cervix and it became pretty obvious what had happened at that point.
Yes, you can shed lining while pregnant (even if there isn't a loss involved) it's called "decidual bleeding" and there is a nice writeup here
Early Pregnancy Bleeding But it's not only that, it can also be from a subchorionic hemmorrhage, placenta previa, losing a twin, or even completely unrelated from the cervix area and not even be in any way jeopardizing a pregnancy.
So, what I want you to be on the lookout for is the possibility that it actually IS AF and you'll then ovulate within 10-14 days, OR that you have not even ovulated still. Sometimes people will have a rise, and then another rise, and then only after that will they O. So for all we know, this is midcycle spotting, O is yet to come, and there will be another rise after this. I just don't want to assume anythign at this point that will lead to us missing an opportunity.