I can totally understand that you would perceived all the pain and suffering you are enduring as punishment for past misdeeds. It's difficult to live with so much pain and we naturally want to point at something, blame something for all our suffering. I've had my share of pain, physical and emotional and it can create a lot of confusion about our self and our worth. But you are not being punished for past sins. Our soul doesn't perceive anything that we have done in the past as a sin. That is a human perception. Everything we have ever done or experienced in this life or another is simply a learning experience. Some good some bad but none of it wrong. The idea that you have sinned in the past could be partly the source of your pain. But whatever is the source, what I have learned is that pain is merely a signal that something within us has not been addressed and is looking for attention.
Our human self gets caught up in the whole story of being human and what society says our life is supposed to look like and what we are supposed to be doing with our lives but sometimes our soul has other agendas, not because we are less deserving than others or are being punished for past sins. Mainly because the issues we struggle to heal within us have basically gotten us to a point of being stuck unable to move forward until they have been confronted and healed. so though I can't say why you are in pain or what your soul had in store for you this life I so suspect it isn't to merely cause you suffering. Your soul chose a very difficult life, that is for sure, but the main goal is to heal the things that cause you the pain.
I would not necessarily discount your dreams as not being helpful. The content of the dreams may be pointing to the source of the pain even if they aren't directly giving you answers to why you have pain. I would keep trying to work with the dreams since you seem to have a good access to lucid dreaming. Maybe try and ask to be shown what you need to know to heal this situation. I know for my pain I had to work through a lot of layers to get to the root of it all so not all my questions were answered directly or immediately but I did get access to what I needed to know at the time. I suspect when we aren't given the answers we are looking for we may need more information first so I would myself, just keep asking for help and guidance and look at everything that came through because we never know what might shed light on things for us.
In any event, I personally see all of life as symbolic, not just dream content. The heart is related to love and unhealed issues in this area are generally focused on self love. This could indicate an issue with how you relate to yourself. Maybe some underlying self hatred or feeling unloved. Muscles are related to strength and power. They help us move about the world. so this issue may be robbing you of standing up for yourself or being able to move about the world. So it is very possible, despite your human goals that you have set for your life, your soul may be looking to work on other things. Now here is the thing. It is also possible that your life lessons are intertwined with other people. Sometimes we take on difficult lives of suffering so as to be of assistance to others in their life lessons and nothing more. Regardless, what is happening isn't because you are being punished. Your soul definitely has some challenging plans this life but it isn't because you deserve any of it. It is a sign that you are strong enough to handle it. It may not feel that way to you but you are.
I do hope that you can get to the source of your pain and get a diagnosis for your illness. I send you love and support.