Can you get false positive pregnancy tests

Patient: Hi,Hoping you can help me?I am 10 days late on my period, I have had 2 positive tests and a number of negative tests.My symptoms keep coming and going. I had a miscarriage in Aug 2011 and am so worried, I have a doctors appointment today, can i ask them to do a test for me? will it be accurate though as appointment isnt until 4pm!Could the positive tests be wrong? I have no bleeding or crampingThank you in advance for your advise