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All the symptoms you have mentioned show that you have anxiety
.In anxiety , set of symptoms like palpitations , chest discomfort
can occur , causing your symptoms.There are studies showing fall in potassium levels associated with anxiety.So , probably your main problem is anxiety which is manifested through low potassium levels.
I advise you to visit your Psychiatrist
and explain him your symptoms.Careful observation and good counseling will help you treat these symptoms.