Swashy, I have this problem too. I hate it and it makes me worry about having bipolar or some other thing because years ago I read that it was a symptom of something. But lately I have realized this guilt is inversely related to how I feel about myself. When I feel bad about myself, I have more guilt. When I've been productive and accomplished something that was important to me, the guilt doesn't hit as much. I think KraftieKortie hit the nail on the head: do some things to improve on your lifestyle, send cards to people you know, letting them know you were thinking about them. Most people like to get mail.
Do you think it may be a piling up of guilt from feeling like you fail at a lot of things? I know that we aren't always connected with our feelings and I think things kind of get "backlogged" like an emotional overload that doesn't have a name or any particular cause. I wonder if it all mixed together makes the same physical feeling as guilt does.
Are you are perfectionist? Do you place a lot of pressure on yourself? Sometimes I wonder if the judgment we sense or expect from others is coming from ourselves instead and our own expectations of ourselves. I get this from my first paragraph above, how it seems to be more under personal influence.
I used to have the social guilt too but I'm not sure why or what it's from really. I think it might have been because I used to have this impression that other people my age thought I was a "joke" and "mentally ill" or "stupid" or not a legitimate person. Do you have this impression from others too?
I am glad you posted about this. You aren't the only one.