When I was little I used to have bad panic attacks from going out to dinner, sleepovers, or even the movies. It eventually went away and now it just started to come back. I've been in a relationship for a long time and we had a fight a few months back that shook me up. I seemed ok but now I freak out when my boyfriend seems stressed or mad because I start to think it's something worse. For example, we could have a perfect day and then he seems tense on the phone. I panic thinking he wants to break up even though a week ago we stated that we had no reason to break up (believe me we've been through a lot). I can't seem to get rid of my thoughts and calm myself. I tend to breath fast, heart beat increases, can't eat because I'm nervous, such panic that I feel like I'm going to break, and of course sometimes crying. Any self help to overcome my fears/panic? I have never been diagnosied with any anxiety/panic disorders, and it's not always about my boyfriend (others are friends, etc).Ideas?

The thing you need to do is BREATHE. You can't panic if you are breathing properly and it IS possible to control your breathing when you are panicking. Breathe in slowly and deeply through your nose and out through your mouth. Fill your stomach with air, not just your chest. Do this three times and the worst of the panic should be over. Then continue to concentrate on your breathing while breathing normally (still breathe with your stomach and not your chest)
Do that for as long as it takes to feel calm and then begin to sort out your rational thoughts. Think of what is really going on, not the horrible what if's and maybe's. Think of the love between you and your boyfriend and all that you have been through or what ever else it takes to keep calm.
Some people like to envision a safe quiet place while and meditate on that for a while. That helps too.