So here's a question from a few years ago that touches on pain while exercising. There are good answers, and it's great content for our site.
Here's another from just now, that is already gathering the close votes because "you should go see a doctor."
Sometimes there are legitimate medical issues going on and people really should go see a competent provider. But anyone who's been training for a while knows that a core aspect of training is knowing your body, and one of the major ways your body speaks to you is through pain and discomfort.
A big part of physical fitness is knowing what and how to work with some types of pain. I feel like we're really knee-jerk kicking everything out these days the minute "pain", "discomfort", or "weird feeling" shows up.
There's just no way that every fit person is seeing a doctor every time they have a light muscle strain, etc.