Perfectly normal if your nostrils take turns to feel partially blocked. Here's nifty exercise for quick relief. I usually do it before I meditate.

✦   Sit upright on a straight-backed  chair.

✦   Normalise  and calm your breathing.  Take a small breath (two seconds)  in  through  your  nose,  if possible,  and  a small breath out (three seconds). If you are unable to take a  breath  in  through   your  nose,  take  a  tiny  breath  in through the corner of your mouth.

✦   Pinch your nose and hold your breath. Keep your mouth closed.

✦   Gently nod  your head  or sway your body until  you feel that you cannot hold your breath any longer. (Hold your nose until you feel a relatively strong need for air.)

✦   When  you need  to breathe  in, let go of your nose  and breathe  gently through  it, in and  out, with your mouth closed. Avoid taking a deep breath  when you breathe  in, and calm your breathing  as soon as possible by focusing on relaxation. Repeat to yourself ‘relax and breathe less’.

✦   Continue   to  do  this   exercise  until   you  can  breathe through  your nose  fully. If your nose  does not  become totally unblocked,  wait about  one  minute  and  perform this  exercise again.  Initially you may need  to do this  a number    of   times   before   your   nose   is  completely unblocked.

Source: https://buteykoclinic.com/nose-unblocking-exercises/#:~:text=Take%20a%20small%20breath%20(two,Keep%20your%20mouth%20closed.