Does Presence Of Fibroids Indicate False Negative Result For Pregnancy?

I have had a positive pregnancy test every day for over two weeks. The tests are now getting lighter and lighter but I ve had bad low back pain and some abdominal pain. They did an ultra sound and said I have fibroids and that my urine pregnancy test was now negative. Can the pregnancy be hidden from the fibroids or could the fibroids have cause a positive preg test every day for two weeks? I m afraid I was still pregnant and I m still going to miscarry. But my cycles are always so very heavy I won t know if I should go into er or not.