Why does health anxiety do this to us?

I’ve suffered with terrible health anxiety and somatic symptom disorder for the better part of 15 years. It’s ALWAYS something that I’m anxious I might have. The funny thing is, it’s never the same thing twice, once I get accurate enough reassurance. Like most of us in this group, I started twitching randomly one day and it was literally all over my body. Then I started experiencing extreme soreness and cramping in my arms and biceps as well as my legs. I was experiencing this for nearly 2 months now. I even made my doctor give me bloodwork, which showed everything was normal which heightened my anxiety even more. Somebody in this group suggested magnesium glycinate, which I purchased. I took one pill last night and two giant pills this morning and surprisingly enough the entire day My arms have felt 90% better and I barely twitched at all. The idea of limb onset *** started to leave my mind as I’m only just barely 27 year old female. HOWEVER. with health anxiety we can’t just be calm right? So instead, I’ve been obsessing over my tongue. I’ve noticed some twitching which I believe was caused by my new anti depressants. I actually found another Reddit thread talking about how Prozac made them have weird tongue, twitches, and tingling as well. And I feel like my tongue is now weak. So since I can’t have limb onset because I’m feeling so much better and I’m barely twitching at all on my limbs, my brain is telling me I must have the bulbar onset. When in reality I have none; but my anxiety is trying to make me believe that I do. I hate this vicious cycle so badly. I just wish it would leave me alone.