33 weeks Pregnancy & severe indigestion.

Yesterday i encountered severe indigestion after midnight with vomtings, sore burps and pain in upper abdomen may as i had some street food aday before. So when i visited my gynaec yesterday for the same. Their was some gas which was making my abdomen uncomfortable with irritable sounds; being concerned my doc immediately got my abd scan,viginally investigation that so was fine.. then in 1st baby cgg she said u r  getting mild contractions but whenever i was encountering them it looked to me like a gas cloud moving making my abdomen tight and relaxing in no more than few secs. So she admitted me for full day every 4th hr cgg monitoring but all of them were fine with average fetal heart beats rate of 138. She administered antibiotics like taxim, metrogyl, dns and rns.Now she put me on 5day antibiotic saying i had some stomach infection. My main query is that she has prescribed me progesterone 300sr for 2weeks. but why dont understand why to have them? plz guide in detail for my concern