Hello! I Have A Family Physician And Have Been Diagnosed

Hello! I have a family physician and have been diagnosed with sinus tachycardia and pvc. I had some lab work done because of aches and fatigue. These labs came back today with low vitamin D and B12. I was told I also have mono. I would like to know how this all links together and how each diagnosis affects the other. I'm really concerned because I'm currently on Toprolol (200 mg) and a calcium blocker to slow my heart rate and I am still consistently having pvc. I am currently waiting a referral to a cardiologist through my physician.