Have you tried reading some of the anxiety books? They are designed to help you reprogram obsessive thoughts and they do help. One that springs to mind is by Claire Weekes, called "Peace from Nervous Suffering", it's very good and helped me a lot to deal with the panicky moments.
Someone mentioned the other day, acupuncture, but I suppose you would need to be strongly recommended to someone to get a person that is really good. It is supposed to work very well if it's done right!
Anxiety and Panic can definitely come and go. That is what is so very frustrating about it. You can be having a great couple of days and then out of the blue be down in the dumps once again. That is part of the cyclical nature of this in my opinion. It really hasn't started all over again; you are suffering from health anxiety and you need to break out of this pattern of thinking; I know it is much easier said than done. Are you currently seeing a therapist about this? If not, I suggest you find one that you are comfortable talking with....this takes work, but gaining the knowledge about it will give you the freedom to tackle it. Keep us posted.