I don't know if the cause of what you're experiencing will match this,
@Sammyiam ... I experience very similar things at times though.
What helped me is reading some about secondary structural dissociation. Some of us have sort of varyingly complete mental "pockets" from earlier life contexts that got frozen in there because we could not deal with them at the time and survive (or so some deep unconscious part of our brains 'thought'.) A deep mental part of us is motivated to resolve the feelings in there; it's taking us energy to keep the separation, but integration still feels dangerous to that part.
A description of my current approach... (Based on what I'm learning from a good trauma therapist, which I really highly recommend; "grounding" skills and support are so crucial!!!)
One way our brains can deal, is letting the "bubble" from a "pocket" come over into our normal everyday lives a bit. Just a bit! A nice, safe, little bit. For me, it can feel like an overlay, where I'm sort of multitasking; other times, the emotions feel like they are the only reality, but I still (can try to) cognitively remember that I just had felt better 10 minutes ago, and yes this must be one of those pockets, what is it though??? Figuring out the context and what the problem was is really hard, it's so out of my current context. A lot of snippets are sort of side parts to old contexts, I'd even squashed connections to those -- like what the old basement looked like. Then I might need to work on grounding, as I still need to function and survive in the "real world"...
The emotions in the "bubble" are extremely different for me than my current context emotions, and the part of my mind that "wants" me to deal with the stuff as "it" feels I am able isn't really the conscious "me",
thus the weird and fast changes in emotional states. However it's currently only happening over a basic feeling of increased safety for me. Much better than my old life, where the world really did feel largely unsafe at times.
Anger at myself was an old coping mechanism, and comes up with some "pocket" stuff. The "pockets" have whole old ways of being in them, but I'm still also in the present, which is important to keep for integration into the present.
Emotions in a "bubble" feel different than current ones for me; there is sort of a vague feeling of stale air with the emotions for me. Hard to describe.
If this resonates at all -- be good to yourself, work on feeling safe and grounding skills... integrating these feelings and memories is very good for you long term, and I feel "lighter" afterwards. Plus areas of tight muscles get a little better for me at times afterward.