Well, I googled it, and what do you know – sensitivity to low pressure weather systems is actually a thing.
Apparently, reduction in barometric pressure can lead to migraine headaches, painful joints, sluggishness and feelings of depression. Sounds about right. Some people are more sensitive to it than others. Meteoropathy is what the scientists call it when they induce it in their lab animals (poor mice!)
See, I’m not a hypochondriac after all!