Hi there!
I'm not all that knowledgeable about social anxiety, as I, myself, am currently recovering from a more general form of reactive anxiety, but I hope to be of some help.
I would say that anxiety, in all its forms, formally comes under the umbrella of 'mental health issues', though different people probably have different opinions about its classification.
People may realise that they are experiencing social anxiety, because their feelings go beyond mere fear - they experience overwhelming feelings of fear, panic, discomfort, etc. in social situations. These feelings may be accompanied by physical symptoms such as sweating, shaking, breathing difficulties, etc. (I'm sure you can read up about this). Even contemplating engaging in a particular social situation may bring on such feelings and/physical symptoms.
As regards seeking help, I've been told that counselling and (particularly) CBT are the most effective methods of treating social anxiety, coupled with medication (if necessary). There is plenty of help and support out there for overcoming this particular form of anxiety, that's for sure!
I hope this is of some help to you,
Take care x
P.S. Don't be afraid to seek help if you think you need it, even if it's only to reassure yourself