Heart palpitations developed overnight when used fake marijuana (herbal incense)

Hi,  I smoked this herbal incense called "peaceout" a year ago and ever since that day I have had heart palpitations which developed overnight. There could have been a chemical in the substance that is under the FDA ruling for concern, but I am not sure. Before that I had no problems with my heart. I have gone to medical doctors and got an ECG, EKG, Stress test, Holter monitor, and blood test done. All the the results were normal. I was diagnosed with a fast heart rate since my resting heart is around 110. Before that night It was usually around 75. Basically I have an usual awareness of my heartbeat and It feels like it is spiraling and flapping around. Also, I went to a psychologist and I was given Prozac 20mg. She diagnosed me with internal physical anxiety.  After about 6 weeks of taking that I noticed an increase in my palpitations so I stopped it. I am trying to find a product or test that will determine if I have too much of a neurotransmitter which is causing my physical symptom of anxiety. Also, I am trying to figure out a way to turn my physical anxiety into mental again if that makes sense. If anyone has any suggestions on how I should go about this that would be greatly appreciated and may God Bless. Thanks in advance.