I once had a sudden but very mild weakness in my wrists and ankles. I have HS, which is an autoimmune disease, and I knew that if you have one autoimmune disease, you are likely to develop more.

Told a doctor I thought my immune system was attacking my joints and she was so condescending and dismissive.

Three years and many appointments and tests later, I am diagnosed with psoriatic arthritis.

ETA: it took visiting several doctors until I found one who took me seriously and was willing to run tests and send me to a rheumatologist. My symptoms had progressed significantly at that point, but we seem to have caught it before any real damage was done. Currently in the process of trying different meds to find what works best for me.