Hi, I Had Taken A Couple Home Pregnancy Test. One

Hi, I had taken a couple home pregnancy test. one i took friday night and it came out a very faint positive so i when i woke up saturday morning i took another one and there is no doubt it was positive. so sunday night my husband wanted me to take a digital one and it came out negative. I called my dr Monday morning to make an appointment and she told me that i was pregnant that it is rare to get a false positive test. i have been freaking out because i am cramping feeling like i am about to start my period but a week later and still have yet to start so i tried another test after i got home from work today and it was negative but not the same brand as the one i took friday and saturday. I am so confused and my dr can't get me in for three weeks. I just want to know why i am cramping and feeling like i may start if i had two positive test. Is this normal for me to be cramping and to get negative test results after a positive