I am so sorry to hear about all the losses you have suffered. One would be enough to make you feel upset, sad and edgy, but so many in such a short period of time is overwhelming. As you were describing the losses, I was thinking how out of control you might feel just hearing about all of these deaths. When someone dies, there is a lot of sadness but there is also a feeling of helplessness. Not that you could have done anything, but the fact that a loss has to be faced and there is no real way to do anything to get around your grief or the grief of others can make you feel hopeless and helpless. I think this played a big part in your anxiety. All the losses along with the change in medications are related through the out of control feeling you get from both.
There is also a sense of facing your own mortality. Although you know God and are saved, the idea of death is not easy to face. Even Jesus did not want to die. So facing the thought of your own death can be frightening and bring on a lot of anxiety. As time goes on you gain back that feeling of safety but it does take time.
I do not think your cats fighting like they did is odd at all. I used to have two cats and sometimes out of the blue they would do the same thing. Not for as long as your cats, but it always seemed connected to something going on in our home. Animals are so sensitive to what goes on in their environment, I think more than we realize.
Trusting God is a good answer to your medication anxieties. As you know, He will never give you more than you can handle. And He is right there with you.
Sleep apnea is more of a medical issue. I do have some experience through the people I have worked with who have had to go through what you are going through, although I might not be able to answer your questions fully.
Have a good day, Rita. You are in my prayers,