I completely agree with SteveinFrance. Whenever feelings come up without an immediately apparent cause, it is because they are stored emotions from our past, rather than anything to do with the present. Unresolved emotions never go away, but are triggered by current life events.
The book he recommends by Pete Walker is an excellent choice to help you understand this phenomenon of emotional flashbacks, but I would only suggest that you do not believe the author when he says that emotional flashbacks never really go away; they do and they will.
The trick is to stop avoiding the feeling or attempting to escape it; I know that this is difficult and counterintuitive, but think of the feeling as coming from a part of you that's deeply hurting, emotionally, and needs love from you – the only person that is aware of it and is able to help us – to feel better. So, approach it with love, by which I mean simple gentle kindness, and stay with it, kind of how you might stay with a friend who had just gone through a painful break up and is feeling awful, and simply needs someone who is compassionate to be around him or her. Let that compassion flow from you to the part of you that's hurting inside, and you will notice that it is easing up.
The book he recommends by Pete Walker is an excellent choice to help you understand this phenomenon of emotional flashbacks, but I would only suggest that you do not believe the author when he says that emotional flashbacks never really go away; they do and they will.
The trick is to stop avoiding the feeling or attempting to escape it; I know that this is difficult and counterintuitive, but think of the feeling as coming from a part of you that's deeply hurting, emotionally, and needs love from you – the only person that is aware of it and is able to help us – to feel better. So, approach it with love, by which I mean simple gentle kindness, and stay with it, kind of how you might stay with a friend who had just gone through a painful break up and is feeling awful, and simply needs someone who is compassionate to be around him or her. Let that compassion flow from you to the part of you that's hurting inside, and you will notice that it is easing up.