I wish I had answers for you, LBD, but I obviously don't. I'm just so sorry you're in so much pain. And my deepest condolences in regards to your father.
Just a couple of thoughts.
First of all, you're obviously going to go through a period of grief in regards to your dad, even if the relationship was troubled. Grief is not a mental illness but it can extend for a long time and be very painful. I don't know if you have read up on that, but you might find some explanations for how you are feeling in articles on that. There may very well be such articles on this forum. Skeezyx would know.
Secondly, I wonder if you have pretty much always felt the way you're feeling now, or if it has come on only in the last couple of years, while you were experiencing the illness and death of your father, and the troubles at work, which I'm glad to hear are no longer a problem.
Many hugs... ((((((

))))))