Suggest Treatment For Recurring Tachycardia And Arrhythmia

I have atrial fib which started 4 years ago. I had extensive tests and was treated by a holistic MD through vitamins and lanoxin .225. I had regulr blood tests from my office.I have done very well until I retired from chiropractic and took the board of another State to practice part time. The boards turned out to be difficult, and I believe the stress has restarted my tachycardia and arrythymia. I have been getting my lanoxin on line and I have reason to be believe the last batch was of no value since Have digressed. I am waiting to see my digitalis levels which should be in Monday. Can you prescribe me a stateside prescription if needed? Don Selvidge age 69