Positive pregnancy tests but no baby?

Has this happened to anyone else? I tracked my ovulation in June. When we hit peek June 29th we got busy and 2 weeks later I had a positive pregnancy test. Then for a week straight I kept taking tests. My husband just couldn’t believe it! All positive!!!! So assuming I was pregnant, I went on with my life as a pregnant women. If that makes sense. So today (7 weeks pregnant) I am at a party and go to the bathroom. When I looked down I had blood all in my underwear. I was so scared I was having miscarriage. My doctor told me to go to the hospital and get checked out. (Also my first doctor appointment Wasn’t scheduled till this Thursday, so I hadn’t seen a doctor yet) long story short, I was having a my cycle. After the ultrasound there was no baby. They said that my body thought there was a fertilized egg but it really wasn’t. Anyone else ever experience this????