Not responding to pump- rant

I’m needing to pump since due to illness baby isn’t nursing often and I’m also sick and feeling a low supply/ pain. For some reason one side will not respond to a pump at all😬! Talk about uncomfortable! I can still hand express some but it’s so much work and a pain. End rant. Is this common, or possibly a sign of losing supply?

Note with my first I exclusively pumped with no problems, and alway had a lower supply on one side; but this is the first time I have pumped with this new little one since he usually is always wanting to nurse