Doctor appt today : ( please read

Well I had an appt today at five weeks. Because of a previous ectopic (in April) my dr wanted to see me early on. He did an ultrasound and I was so convinced we'd see something but there was nothing. Absolutely nothing. I feel so disheartened and scared that this is another ectopic and now I'm having really intense cramps in my back and on and off in my lower abdomen. I had my blood drawn and will go again on Friday. Anyone else have a similar experience? Good or bad outcomes?