Fitness

If you are able, consult a soft tissue medical professional in your area (physiotherapist). They’ll be able to do a more thorough diagnosis than your GP.

Getting ahead of it - chiropractic is a scam.

If the doctor is right, then you're right about waiting for it to get better. If it's joints, then (as you can't train joints) you have to change something. If it's muscles, it should get better after several regular (once a week or more often) trainings - it will switch from sharper feeling to usual softer aching that you feel when your muscles are exhausted.
It's really nice that you consulted with a doctor - if you are not experienced, it's better to ask. It can be also useful to tell your trainer (or someone you train with, if there is) - maybe they will look closer at your technique
In most kinds of trainings or sports, it's always about "raising the ceiling" of exhaustion to the point where you don't usually reach it. If you can climb to 40th floor, you won't feel pain after 10. If you can stand in a plank for 5 minutes, you won't feel discomfort after a minute.
Just be careful and you can train up to the point where you will feel generally easier with your body, less tired after a normal day, and "good kind of tired" after an active, "sporty" day.