I know of no mental health disorder in which blushing is a specific diagnostic symptom. While blushing is not a specific symptom of any one particular mental illness per se, it may be associated with social anxiety disorder. Individuals with social anxiety or social phobias feel particularly anxious in the presence of other people, especially when they are the center of attention. These symptoms seem to match your experiences.
Among individuals with social anxiety disorder, everyday situations can be fearful. Individuals with social anxiety often do not feel confident about themselves. Because of this, they tend to avoid the situations that make them anxious. In the short run, avoidance decreases anxiety but overtime, it can increase its severity.
Can social anxiety be treated? The answer is yes. Cognitive behavioral therapy (CBT) has been shown to be effective. CBT is a treatment that addresses both behaviors and thoughts related to anxiety. Generally CBT lasts for approximately 12 weeks but the length of treatment depends on problem severity. Some CBT therapists require clients to complete homework assignments such as recording your daily moods or feelings. Therapy sessions can be conducted individually or in a group setting. Another very effective treatment is exposure and prevention response (EPR) therapy. Usually, EPR is used to treat individuals with obsessive-compulsive disorder though it has been effective for other types of anxiety disorders.
Another idea is a concept called “hyper-intension.” I’ve written about this concept in other answers but I think it may apply to you. The idea was written about by psychiatrist Viktor Frankl in his 1946 book Man’s Search for Meaning. He believes that when a person intensely focuses on their fear that attention may have the unintended consequence of producing or increasing the fear. In other words, a person’s fear is made worse by their intense focus on it.
The solution to this problem, Frankl says, is to apply a technique called “paradoxical intention.” Paradoxical intention means that you do the opposite of what you would normally do in response to a fear.
What is encouraging about your problem is that it has improved. The reason for this may be related to an increase in self-confidence. Another reason may be because you have trained yourself to be less anxious over time. There may be other explanations as well.
When you feel the blushing occur, I would encourage you to remain in the uncomfortable situation. If you force yourself to endure your anxiety it will diminish. Don’t avoid a situation because you think you may blush. As I mentioned earlier, avoidance could make your anxiety worse.
Also, keep in mind that while you may focus on the blushing other people may not notice. If you surveyed the other people present when a blushing episode occurred you would likely find this to be the case. Even if others did notice they most likely would not comment. Blushing does not necessarily have a negative connotation. In fact, some people may find it endearing.
If this is a problem that continues to bother you then I would encourage you to see a therapist. Because your fear is so specific (i.e. blushing) and it has improved over time, it may only take a few targeted therapy sessions to extinguish. I’d highly recommend it. I wish you well. Thanks for writing.