crystal,   Thanks for your question.    First of all, I don't think this is a heart attack.  Chest pain from heart disease is usually effort related, but certainly can occur at rest if the disease is severe.  However, cardiac pain does not change with position.  Though nausea and vomiting can occur, the freezing and teeth chattering does not fit.   Reflux can be severe in some people, and certainly can be related to position, as well as nausea and vomiting.  Again, the freezing and teeth chattering are not common, though people can have varied symptoms after an episode of vomiting, with sweating, chills and other complaints.  In short, reflux is still a possibility.   Another cause that should be further investigated is gallbladder disease, which can be positional, but not commonly.  It often is associated with nausea and vomiting, and the pain can be very severe, lasting a few hours.  Many patients are admitted to hospitals with presumed cardiac pain, when the real cause is later determined to be their gallbladder.  Again, the freezing and chills may be related to the vomiting, but another possibility is a transient episode of bacteria entering your bloodstream.  If a gallstone blocks the duct (or tube) that drains the gallbladder, sometimes this causes bacteria to be released into the bloodstream which can result in the chills.  Of course, this is all speculation and needs to be looked into.   You must make an appointment with your physician for an evaluation of your symptoms.  He will ask further questions, perform a physical examination, and may request blood work.  Be sure to discuss your gallbladder, which can be evaluated with an ultrasound of your abdomen.  If needed there are further tests to prove or disprove this diagnosis.   Should you have another severe episode, you should go to the emergency room.  For mild symptoms, try Gaviscon liquid which is an antacid that foams up and protects the esophagus.  If this is reflux, this should provide quick relief.    Best wishes and feel better.   Martin Cane, M.D.