Hi Tinkerbell
I would like you to know that I have these feelings too myself. As I understand it, they are what you might call a defense mechanism. If you feel in a panic then its because there is something you need to do, but you haven't worked it out yet. If you knew what to do then you would not need to panic hon.
I would say, deep breaths and listen to your mind. Check in with yourself at lots of times during the day. Feel where you are tense, anxious or upset. Perhaps your shoulders are up around your ears, or your tummy is doing an impersonation of a washing machine or your brain is obsessing about things that are not so important.
Focus on something you love, for me its the sound of the wind in the trees or a Mozart piano concerto; but its what is important and heartening to you.
I can reccomend a CD I have that helps me to calm down, relax and sleep. You have to really get into it and do everything you are told to (only relax, think of a garden, nice stuff like that) I tried it first night and thought this is rubb......... next morning I felt great, best sleep since I was a child. Its by Glenn Harrold (I have no self interest in promoting this, it works for me. Amazon have it.)
I don't think you have a phobia. I would suggest perhaps you are on a less than conscious level trying to come to terms with your own mortality, or that of someone close to you. We are all gonna die, that's the easy part; living is the hard part and living WELL (best revenge!) is harder.
Relive your lovely weekend, and don't be hard on yourself for feeling on edge. Something is, I feel, trying to get through to your conscious mind and the more agitated you feel, and maybe even afraid, the harder it is.
Did you ever work on Maternity? Or do you have children? Sounds like you may be giving birth/life/presence to something important to you.
Best wishes, Auracaria