Hypochondria Support Group
Hypochondria refers to excessive worry about having a serious illness. Hypochondria is often characterized by fears that minor bodily symptoms may indicate a serious illness, constant self-examination and self-diagnosis, and a preoccupation with one's body. Many individuals with hypochondriasis express doubt and disbelief in the doctors' diagnosis.

I recently had two doc appointments where my blood pressure was slightly elevated. I have been ruminating nonstop since then and terrified to get my blood pressure checked.
Like you said, it can go away for months, then it hijacks your world. Sigh.
I wish you peace.
I have had the same experience with COVID causing my anxiety to come back after 6 years of feeling pretty good. It is really frustrating. It has now been almost 3 months of anxiety, hot flashes, insomnia, and poor appetite. I still don’t have my full sense of smell back.
I am sorry you are experiencing this but it is reassuring to hear someone else has had the same thing as me:)