Jamie, hello and a warm welcome to HW. I am very happy you found this forum too 
We are a warm and supporting bunch of people here so I'm glad you have shared your story. Panic disorder doesn't mean you have to panic "out of the blue". It just means that you have panic attacks. Even if you know they are coming, those symptoms you described are a panic attack. You can have cued panic attacks which means you know when they will happen (flying for example) and uncued panic attacks which are the ones that come out of nowhere. Both of them are blech in my opinion!
Do you mind telling us what meds you are taking? Maybe you need to change the dose or the med, it might be a good idea to see your doctor for advice on that one. I'm sorry that you are feeling like you are having a nervous breakdown and crying so much. It must be really stressful, especially if you are fearful about losing your job. What makes you think you are having a breakdown exactly? Is there someone you can talk to about this (including us of course!), that may be able to explain what is happening? I hope this is of some help Jamie, remember you are not alone in feeling this way, please let us know how you are going.
Again, welcome to HW, you are in a good place
Meg