Yup, feel like that a lot. Often it comes over me like a flash of lightening right in the middle of doing something that I love and it ruins everything. Sometimes it just sits heavy on my chest like a big cat. I can give no insight. It's like the wind. Blows from out of who knows where and away into who knows where. DBT would have us Accept this feeling. Just accept that this is me or you and go on with your day. It's just that often it destroys everything. Sorry you are feeling this way. I hope you can get help.