Yes, I have had this for about 25 years, and from your description, it sounds like an ectopic heartbeat. What happens with ectopic heartbeats is that the heart beats an extra beat and so to correct its rhythm, it will then skip a beat, consequently the thud you feel in your chest is actually the heart rhythm adjusting. They are harmless, although alarming, but you need to have this diagnosed to rule out any other problem with you heart. There is plenty of information on the internet about ectopics.

My father scars the nurses when he is in hospital and this happens to him. I just get palpatations.
This article was just sent to me that explains why fybro and blood flow are related.
http://medicalhealthnews.info/fibromyalgia-myst...

I am a very anxious person and have been all my long life and I believe the ectopic heartbeats are most probably caused by anxiety and nerves. But your pain specialist was about as ch use as a chocolate teapot if he didn't take the time to explain to you how anxiety can affect the rhythm of the heart, how these extra beats occur and why and what is happening in the heart chambers to make you experience the feeling you are getting. I had to get this information from researching on the Internet, and it helped me to understand what was happening in my chest, thus reducing me anxiety about it, thus reducing the extra beats. It is so frustrating to visit a medical professional with a problem that is perceived by them, as being non life threatening and be referred to a psychologist to sort out your sleep problems, when what you really need from him is some reassurance and advice on how to cope with it all. Try reading up as much information as you can get because understanding why it happens will reduce your anxiety about it. I know that the more stressed I am, the more extra beats I will get - and when I am in a more relaxed phase, they will go away again. Good luck🌻🌻🌻

Thanks for all your answers guys. I saw my pain specialist yesterday and I'm never going back there. He didn't listen to anything I said. He told my the heart beat issue was anxiety, didn't give me any tips or help with my lack of sleep.. I'm lucky if I have a couple of hours a night most nights. He told me to see a psychologist for the sleep issue. He contradicted himself throughout the appointment and asked me the same questions four or five times. So annoyed I had to spend money for such a waste of time.

I have tachycardia and this is the feeling I get. Sometimes it's like a flutter feeling or 2-3 sharp heartbeats. I have had this since I was 18. I'm now 50. I was put on a low dose of blood pressure medication to regulate my heart. It helps but not all the time. I also had a bad experience of atrial fibrillation 15 years ago during a bad migraine episode. Symptoms were similar to tachycardia but were continuous for hours. You should get checked by your doctor to determine was is happening. Usually they will do an ultra-sound and holter heart monitoring device for 24 hrs. It's better to know what is causing this so it can be properly treated or monitored.