I am exactly 5 weeks a 1 day late fpr my period and I've taken about 4 test they all came back negative and I went to e.r they did a blood test and that came back negative. What do I do && what could it be?

First why does anyone go to ER for a pregnancy test, that is about the last place to go. You go there for life and death issues. It is also most most costly of all places to test.

But there can be 100's or reasons to miss a period, some women miss one now and then, also other medical issues. Which is why you don't go to ER you go to your doctor.