When someone has a muscle imbalance there are usually two things happening.

On one side of the area muscles are getting tight and short. On the other, they are getting overstretched. The overstretched ones are usually the ones that hurt.
To better explain this, let’s look at an example that I am sure you are familiar with: the rounded shoulders from sitting at a desk. When someone’s shoulders are rounded forward, you can bet their pectoral (chest) muscles are very tight. But the upper back muscles are being overstretched and getting weak.
These overstretched muscles usually cause upper back pain making people think they need to roll, massage, or stretch their back. Unfortunately this won’t solve their problem. Since overstreching is causing the pain, more stretching won’t help.
In this case, the chest muscles need to be stretched and lengthened. The back muscles need to shorten and get stronger. Massage can really help with adding length to the short muscles and I frequently provide my clients with exercises to strengthen the weaker muscles.
This problem is quite common all over the body. Low back pain is another frequent example that is caused by tight hip flexors and overstretched low back muscles.
Whenever you are having muscle pains, look around your body and see if you can see something tight. The cause of the problem might be on the opposite side. Make sure to analyze whether the pain site is a tight muscle or a overstretched muscle. Sometimes it can be hard to tell, so ask a professional for help if you need to.