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I am Dr.R,K and I am pleased to assist you.
Epigastric and pain under the ribs on the right can occur due to issues related to gallbladder, liver, pancreas and acidity.
Since Murphy's sign is negative and there is no evidence of gallstones, pancreatitis, the pain is less likely to be due to GB or pancreatic issues. I presume the USG also showed a normal liver.
So you need to rule out peptic ulcer disease. Since you have mentioned it is a burning pain, peptic ulcer disease is more likely. An upper Gi endoscopy may be done to look for peptic ulcer. Meanwhile you can take prilosec for relief.
The abdominal bloat and gas are other dyspeptic symptoms that point more towards peptic ulcer disease.
You need not worry about the floating stools. High fat diet and increased gas can cause stool to float.
If the bowel movements are still painful get a stool test done to rule out infection.
I hope that answers your question.
Let me know if I can assist you further.