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The tearing pain brought out by the twisting motions is most likely from a muscle or ligament over related to the ribs. Second possibility is as a stretching of the parietal pleura (the pain sensitive membrane over the lung) or the peritoneal lining over the gallbladder or liver.
The major organs are UNLIKELY to be involved as they do not have receptors for this kind of pain. So the origin of this pain is superficial and most likley not serious.
You can cautiously observe the symptoms and see how it evolves. You can take an OTC pain medication like Ibuprofen twice a day with food. Yes you do have symptoms of acid reflex (Ibuprofen could worsen them). So you can take another OTC anti reflux medication like Prilosec once day for 7 days without food.
Increasing swelling, abdominal pain, altered bowel habits, nausea, vomiting, breathlessness, increasing pain are the danger signs you need to watch. In case of any these signs develop you will need to visit the ER.
Hope this helps
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