A major scare

On Wed. 03.14.12 I've been having this major pressure on my lower left abdomen. The feeling was like cramping with no bleeding below the bellybutton... It almost felt like a pressure being pushed out from the inside... at points it's numbing and very very uncomfortable. I felt hot then I felt cold. I thought that I needed to eat something so I had a banana but couldn't hold that down. This would be the first throw up I have done since this pregnancy and I'm at 19 weeks and a few days. I called the doctor and my friend at work drove me there because I was in no condition to get there myself. I can not thank her enough for coming back to my office to check up on me. The pain was so excrutiating all along side my keft lower abdomen. My dr checked to see if the cervix was closed and it was and he heard the heartbeat but did not tell me what it was but said that I should go to the hospital.
My husband picked me up from the office and drove me to the hospital for an emergency check in. They stuck an IV in me gave me some meds and the pain in the lower left abdomen was getting far worse. It was like a muscle spasm of some sort that was spaced about 25 to 30 secs from each other. The doctor said that it could be many things like a round ligament pain, muscle contracting, fybroids, cyst. early contractions (but I was at only around 19 weeks....) I went in for an ultrasound to check but not just for baby. They said it was to check for something that I was so not paying attention because my mind was on the pain and baby. The scan came up fine so that was good. Baby was good too thank the heavens above!!! The heartbeat was 150 bpm. I told the Doctor when he came in that the spasms were 30 sec apart and he pulled a mini ultrasound machine in my room and saw the contractions.... He told me that it could be contractions but the cervix was closed and no bleeding.... I asked if this was a common thing that they see in the hospital and they said no. He had me stay over night and shot some pain relief in my IV fluids. I couldn't keep any food that I ate down.... What a nightmare.... Before I slept I had the nurse double check my little chickpeas heartbeat.... And it was still there but the pain still didn't go away... By morning I was much better still mnior throbbing spasms but I kept my breakfast down. So I was released. Had my pain meds filled at the pharmacy and I had to use it immediately because it came back.... the meds helped but I'm trying to not take it often.... (one... because of baby...two... because this drug is so powerful...) Hope I never get to experience this ever again.... nor will any of you.... The Cause? Still unsure.. but it's not as nearly as bad as it was on Wednesday morning... Till then ... my rest and then next week... an ultrasound to find out the sex of baby.... but I think I am 80% sure based on all of the u/s that were done on me....