This is a really elaborate question.. but I'm very scared, and have been going through this for years. I'm finally giving in and asking any and all doctors for their opinion.

I'm a 26 year old male. 6'2 and 145 lbs. I've been having episodes of SVT since I was 18 years old. About 5 years ago a cardiologist I saw put me on 25mg of metoprolol twice daily. It seemed to help a lot. The episodes happened rarely, and I felt mostly normal. A year or so after that, my symptoms worsened again. He upped my dosage to 50mg twice daily, and scheduled me for an echo and a holter monitor. I had the tests and both can't back normal. I had no episodes of SVT while on the holter, sadly. After he increased my dosage again, I felt normal for a long time. Last March I traveled to Ireland. I was there until May. When I came back to my home, I was out of work for a few months and was living a sedentary life. After a while I started noticing symptoms. I was experiencing numbness and pain in my back, shortness of breath, dizziness upon standing, muscle weakness, heat and cold sensitivity, insomnia, and severe anxiety. I became very depressed and was afraid to go to the doctor. Eventually my girlfriend forced me to go. I was given full blood work and a chest X-ray. Everything came back fine and the doctors attributed it to anxiety/depression and months of inactivity. I felt slightly better after hearing that from the doctors, and went home. I secured a job and felt a bit better, but still felt nowhere near healthy. A year later, I started noticing my symptoms getting drastically worse. My legs would tremble when I walked up and down even stairs. If I tried lifting anything, my arms and hands would shake. I was extremely tired, the pain and numbness in my back had worsened, and now there was a new pain in my abdomen under my rib cage. A constant dull soreness. I also noticed my shortness of breath getting worse. I could no longer even sing or yell without feeling like my lungs were going to collapse. The breaking point for me was one night while I was having sexual relations with my girlfriend, and my heart went tachycardic. 280bpm for 15 minutes. It felt differed than the older episodes I used to have. It wasn't just fast. It was hard and felt like my heart was going to explode. When the paramedics got there, it converted. Since that incident, I haven't been able to have sex with my girlfriend, because as soon as I get excited, my heart starts beating very hard and slow, and erratic, instead of fast and steady as it should. This was in July. It's now November and things only feel worse. I feel like I can't do anything. The symptoms are all too much and too frequent. I'm seeing a doctor who actually seems to care, but I have to wait 2 weeks between visits, and he hasn't figured anything out yet. That's about the end of my story. I just want help. I don't care from where. My whole life is ruined and I feel trapped and scared.

Here are all of my symptoms:

Upper back pain/numbness
Dull pain under ribs in abdomen
Shortness of breath
Heart palpitations
PVCs
Tachycardia
Bradycardia
Tachycardia on standing
Insomnia
Weakness
Fatigue
Blurred vision
Purple fingernails and toenails
Cold and heat sensitivity
Angina
Severe anxiety

I also personally, think I have Marfan's syndrome. I'm 6'2, and 145lbs, and my fingers, toes and limbs are all very long and thin. My face is also long and thin. I just don't understand how I could be this old and not have been diagnosed already. Nobody else in my family has it. The only reason I even know of it's existence is because a friend of mine in medical school mentioned it.

I've also got a black pit for a wisdom tooth in the back of my mouth that's been there since I was 19 or 20 that I've never had taken care of. I know I've heard of tooth problems being related to cardiac problems.

I'm not looking for a cure or a diagnosis, only some insight into the situation from someone in experience. Reading about what COULD be wrong with me online is mostly useless because there are so many symptoms and variables. Anything would be helpful at this point.

Thanks in advance.

If I think of anything else I'll add it.