Odd/ slightly terrifying symptoms

So lately I have had a couple "episodes" per say, that are slightly concerning to me. For the past few weeks I have had odd cramping, as if I was going to pass a blood clot, then havin a sudden sensation of feeling wet, but nothing was there. I then about a week ago my fiancé and I were out eating and all of a sudden a sharp pain shot just underneath my breasts, in the middle where your bra wires come close. It was such a powerful pain that I had to have my fiancé undo my bra to release some of the pressure on my chest. It made me quite dizzy as well as I could not eat. After about 10 min or so the pain went away and I was left pretty exhausted. I literally feel like all of my organs are up in my chest together. There is a possibility that I am pregnant, but so far the test that I took about 3 days ago says negative. I will be taking another test in a couple days, about a day before I will start my next period to double check. Anyone have any ideas of what these symptoms could be? If the feeling persists and I don't start my period, I will be going into the doctors to see what it is for sure but I was just wondering if anyone has experienced anything like this before/ has any insight of what this could be/mean?