The nature of our existence, as you already know, is not only confined to a physical existence. As multidimensional beings, especially if your Higher Self is using parallel incarnations to accelerate your evolution, you will also deal not just with your current life, but also with other selves that are One with you, residing in other realms of existence and/or on Earth, at this time. These parallel selves, probably incarnating on what we call past or present reality, may be awake and conscious of their multidimensional nature, or may not, as sometimes of all these extensions just one or two are consicous of who they are and their role within Creation.
As ascending souls, most of us do not have karma, which is one of the main reason why working with past lives does not work for some of us who have already done this inner work before. This is why entering into a state of silence with your soul and Higher Self/Guides, to retrieve the proper knowledge about your mission in this lifetime is pivotal when you are healing/dissolving something from your past or another aspect of you.
Having said that, it is also vital that you begin to work with all your non-physical bodies, as you keep evolving, for this is the first thing we should do when we step into this path, and one of the reasons why some of the ascending beings are not able to see distinguish what is really occuring in their being because they have not done the basic inner work first. Although, we may not have karma to resolve, it does not mean we do not have in our aura, mental and emotional bodies as well as DNA, still some old memories, programs, implants, psychic debris in our central canal to clear, and many similar issues to heal or dissilve that we have to treat before we can regain more guidance.
The reason why we are being affected by our other selves and feeling negativity - if this is the case - receiving images and dreams or visions - of beings that we are not used to - but that feel as if they were familiar, is because our soul extension is more conscious than they are and we came here with the soul agreement to help them clear their karmic debts as well as to be the ones with the responsibility of assisting the other soul extensions of us on Earth to reach ascension. This involves a huge amount of integrity, discipline and honesty with ourselves to see where we still let our lower self interferes, for we are not alone - as our human self may think - and what we do or/and decide to be, affects other aspects of us and All.