I (22m) got the 3rd pfzier yesterday. i have nephrotic syndrome (from childhood), but it's usually under control. since i woke up today, there are numbness and weakness in both of my legs. this never happened before. should i be concerned?

See your physician for an exam and additional testing, as what is described is not a usual finding after a Pfizer COVID-19 shot.

Those symptoms have nothing to do with your chronic kidney problem but they could be manifestations of Guillain-Barre syndrome which can be a side effect of Pfizer mRNA vaccine. You should go to the hospital ER if leg weakness persists or get worse.

There are several conditions which may cause these findings. An examination and diagnostic testing is recommended. A reaction such as this to the vaccination would be unusual, but should be considered. Watch for signs of shortness of breath.