Note that 135 BPM technically called tachycardia is considered an arrhythmia. But given the constellation of your symptoms I would not focus on this as solely a heart problem. Something no doubt is causing the dis-regulation of your autonomic nervous system or some other part of your body.
This happened to me in March 2004 when I was 56 years old. I was in top physical condition when my first symptom started with muscle twitches. In the next few months the symptoms started to fill a page and the neurologist I was seeing diagnosed me with a motor neuron disease called innervation re-innervation. I said what about all the other symptoms. He gave me brain MRI for the headaches. Told me to see a my PCP for the stomach/GI issues. He tried to separate out all the other problems. I left his care and ended up seeing a top lyme specialist and he started me on antibiotics immediately based on symptoms. I was fed antibiotics like candy. September I went to the ER with a HR of 300. I was in aflutter. I continued to decline. For the next 2 years I was treated by a 2 more top "lyme literate specialists". Aflutter came and went. Finally after 2 1/2 years since my 1st diagnosis I saw an MD who diagnosed me with mold from my house. He ran medical tests that nobody else had done. Many of them abnormal for endocrine system problems. We tested our house and it was high for toxic mold. We moved out and cleaned the house and threw away a lot of cross contaminated things. I started taking a detox protocol that removed the fat soluble toxins from my blood. 6 months later I was 95% healed. It was many years later that heart arrhythmias re-entered my life but this time is was genetics I shared with my brother and father who also had rhythm issues.
I am telling you this story not to talk you into thinking you have mold problems but to stress with all of your symptoms you have it should not go unnoticed that maybe they are all related to the same diagnosis.