Must start getting serious

about helping my son, H, 3 1/2 years old. However the stuff so far I've read seems to indicate the more the problem is highlighted the worse it becomes and doing any sort of 'therapy' intrinsically highlights a problem?. I'm a qualified Speech and language therapist and I'm feeling overwhelmed.
Here's some stuff I got off the net to start with:

Identifying a child with SM
Children with Selective Mutism:
Find it difficult to make eye contact when they are anxious. They may turn their heads away and ignore you. One might assume they are being unfriendly, but they are fearful and just do not know how to respond.
Look blank or expressionless when anxious. In nursery or school they will be feeling fearful most of the time, which is why it is hard for them to smile, laugh or show true feelings, even when they have a wicked sense of humour.
Move stiffly or awkwardly when anxious, or if they think they are being watched.
Find it difficult to answer the register or say hello, goodbye or thank you. This can seem rude or hurtful but is not intentional.
Can be slow to respond to a question.
Worry more than other people.
Can be very sensitive to noise, touch or crowds.
Can be intelligent, perceptive and inquisitive.
Suggested strategies
If the child does not answer the register verbally, allow them to acknowledge their presence in other ways, such as a smile, a nod, a look or raising a hand. A teacher in an infants class encouraged all children at registration to make an animal noise instead of responding verbally, and this proved successful.
Encourage self-expression through creative, imaginative and artistic activities.
Sometimes sit the child at the front of the group for a story, to encourage attention and involvement.
In discussion and circle times, give the child the opportunity to speak and be patient when awaiting a response.
If the child is socially isolated, link them with other quiet, shy children, singly or in small groups. Play games involving interaction between pairs or the group, such as rolling a ball, pulling on quoits, rowing boats, ring games and rhymes.
Try non-verbal activities which require expelling air and using the mouth, for example blowing out candles, blowing bubbles, blowing ping pong balls with a straw.
Make noises for toy vehicles and animals in play situations or as sound effects for a story.
Introduce play with puppets, because the child may 'speak' through the puppet, especially from behind a screen. Masks may be helpful.
Encourage participation in noisy games and rhymes with predictable language such as 'What's the time, Mr Wolf?'
Use activities that focus on the senses to develop the child's self-awareness
This article was written by Alice Sluckin, Chair of the Selective Mutism Information and Research Association (SMIRA) and a former senior psychiatric social worker, for Nursery World, 17 February 2005. The Selective Mutism Information and Research Association can be contacted at 13 Humberstone Drive, Leicester LE5 0RE. Telephone: 0116 212 7411 (Tues, Wed & Fri, 4-7pm). Email: smiraleicester@hotmail.com