The rhomboid muscle can be responsible for pain at the side of your shoulder blade.
Mostly desk workers suffer from trouble in this muscle as they spend lots of time working in a round shouldered position.
This constantly stretches the muscle and will eventually overload it.
When your rhomboids contain trigger points, you might feel pain at the inner side of your shoulder blade and between them, respectively. That is the most common painzone for those muscles.
The darker the red in the picture, the more common it is to feel an ache in the respective area if your rhomboid muscles contain trigger points.
Usually this muscle will give you pain at rest when it contains trigger or tender points.
Pain may be felt when you lye down on the affected side. But also tasks that involve reaching out for something like a cup from the shelf may be painful.
In the latter case the muscle gets stressed via a stretch/elongation.
Actually the rhomboid is not a single muscle. There is a rhomboid minor and a rhomboid major. The r. minor is the upper and smaller one and the r. major the bigger and lower one.
The muscle runs from parts of your cervical and thoracic spine to the margo medialis – the inner side of your scapula/shoulder blade.
Their functions are versatile.
The rhomboids mainly help to adduct your arm and pull the shoulder blade medially towards your spine.
Furthermore those muscles help to stabilize your shoulder blade in lots of activities of daily living – e.g. walking -, when your upper arms and thus your shoulder blades are moving.
Here I want to distinguish two things. Firstly, active stress on the muscle, and secondly passive stress.
Active stress refers to activities like gymnastics where you have to keep your shoulder lots of times tight and pulled downward in order to maintain proper and upright form. Among others this requires forceful contraction of your rhomboids, especially of your r. major.
Without proper rest and balance through stretching and relaxation exercises, or if you are not used to this kind of work, this may overload those muscles.
Let us consider now the passive stress. A round shouldered position means that your shoulders are rotated inwardly permanently – at least more or less –. This means that your shoulder blade will rotate outwardly – if you were watching it from behind –.
As you know by now, the r. major pulls your lower shoulder blade towards your spine, you will understand that a round shouldered position will lead to an elongation of the r. major. It has to, otherwise the movement/position – round shoulders – would not be possible.
This way the rounded shoulders put passive stress, in form of stretch, on the rhomboids.
As the rhomboid muscles lye under your trapezius you will not be able to feel them directly.
This should not trouble you at all as they can be reached easily through massage. On top, it is not hard to locate the right spot to do so.
A massage ball is the tool to go for massaging rhomboid muscles.
Of course, you can also use a cane for massage.