I need some help dealing with this situation. How can I cut the office noise around me, people speaking, or me thinking that people are going to harm me. Literally, I feel I am in a survival, defensive mood all through the day.
Typical symptoms of depression and sleep problems include all of the above.
The thoughts that people will harm you are mostly anxiety related, but will be greatly aggravated by poor sleep.
You can do absolutely nothing about noise or people in the office. The only thing you can change is yourself. And qualified medical help is the best course of action to do that.
I have little doubt (not least because I've had PTSD for over ten years), that your doctors first priority will be to get you sleeping regularly and well. Typical and reasonable treatments are mild, low to moderate dose anti-depressants but they may do something else to focus on the anxiety.
I'd strongly recommend, from your comments and as someone who has been there, that you take some medication that your doctors prescribe. Seek a second medical opinion if you have worries, but from what you describe you need to open yourself up to the need for, at least, short term medication.
Taking Vitamin D and Aleeve pills everyday
Just to flag this as worrying. Aleeve pills are, if I understand it, painkillers. Unless you have an ongoing health issue that causes serious pain (not the odd ache) then I'd worry you're abusing painkillers to compensate for your real problems (a not uncommon behavior).
To put this in perspective for you I also have arthritic knees and that does generate some pain every day (and all day). I generally do not take any painkillers. I'd suggest you void painkillers unless you've been advised to take them by a doctor or it's an exception - e.g. one day a month or maybe week. Painkillers can cause other medical problems if used for extended periods without medical need.
If you're suffering headaches, and I'd expect that if you're not sleeping, all those aches and pains will probably go away if you deal with the sleep issue.
So again I'd recommend take whatever medical treatment is offered from qualified people who have reviewed and examined you.
In case you have not, you must inform your doctors that you are taking painkillers like these every day.
I am very skeptical about the therapies and did not take any drugs that the doctor prescribed due to negative implications.
Well, I'd reconsider those choices. I appreciate and respect that you may not want to be on these drugs long term, (I didn't), but in the short term it's part of a necessary treatment to stabilize you and get you functioning better.
Therapy may help. It's not a guaranteed cure, but you need to give it a try. Maybe this won't be the right time for it, but keep an open mind.
Should I tell my clients, and managers that I have health issues and anxiety disorder or take a health sabbatical?
Not your clients. Never them.
I'd suggest that you discuss telling your employers (perhaps HR) with your doctors. They will be better able to gauge your needs that I would and would be more familiar with your circumstances.
Likewise your doctors can advise on whether a sabbatical is advisable.
From my own experience I think you'd find that while the anxiety symptoms are hard to shake (therapy can help with strategies to deal with that), dealing with the sleep issue would be of enormous and relatively quick help to you.
So first and foremost find a way to deal with that by consulting with the medics and respect their opinions.
Defer decisions about talking to your employers about this until you have first addressed the sleep issue to some extent and feel more rested.
If they start to ask you about your performance, I'd suggest you say that you have some health issues and it's early days with the doctors. This will tell them you're aware of the issue and addressing it as best you can. Be open to the possibility of moving to a position (if possible) with less responsibility if they suggest it.
You may indeed have to make changes to your life, but do not rush into anything with work.
I can only hope that you are able to take and benefit from the medical help you are offered and I offer you my best wishes in this regard.