We wish you a warm welcome to Healing Well; this is a great community to be in and you will find that many members here will be able to give you help and suggestions.
First of all, you're not going crazy, as you said - I just think you are dwelling on things. Are there stressors going on in your life right now? Do you think those are causing you to as you do? Are you seeing a therapist? Are you on any meds that can help with this? If not, may I suggest that you think about these options.
I believe that panic can come and go especially if under a lot of stress and yes depression often goes along with it. If you can't get to a therapist, you may want to try the free CBT course that is online. I will bring that thread up to the front for you so that you can take a look at it and maybe try. If you don't know what it is, it's a way of changing your negative thoughts and replacing them with postive ones. It has a workbook that saves where you are so that you don't have to do it all at once. Many people here, including myself, use this program. It works for some, but doesn't always work for others.
I hope this information has helped you, even a little bit and I'm sure others will post who have had/have experiences such as yours.
Please keep posting to let us know how you are doing and so that we can continue to help you. Again, a warm welcome to you from the Healing Well family.