Modification to siret / siren and worried about losing health care?

In January I went along to the Chambre de Metiers to add an activity to my existing Siret number. The APE was changed. After having my Carte Vitale stolen at Stansted Airport in March I am in the process of getting a replacement (and have just sent off the identity photo to RSI) - but this morning I have received a letter saying that from January I am no longer covered by RSI branche commercante, but from RSI branche artisan.

Aussi nous avons procédé à la radiation de votre compte Commercant avec effet du 25/01/2011’.  Si vous ne reprenez pas une autre activité vous faisant relever d’un nouveau Régime Obligatoire d’Assurance Maladie, votre droit aux prestation auprès du RSI est maintenant pendant 1 an à compter de la date précitée.

I have always understood that the auto-entrepreneur system is so that people who are just doing a little hobby business can legitimately carry on and pay tax on any sales that may be made. My sales have been minimal as I have operated very very part time - so I am well under the base rate. However, in January I added another activity which would indeed hopefully become my main activity. Since February though I have been having health issues - and indeed have to go to hospital for an op on Thursday and will need ongoing treatment following that, so any future auto-entrepreneur income is likely to be fairly low for the forseeable future.

What should I do about my current cover? And what should I do regarding the fact that I will be under the base rate for pensions etc.? I am not concerned about the income as my husband’s pension is sufficient, he is now covered under an S1 form. It would be a disaster for me to lose health cover at the current time. Can’t find what radiation means relating to my account, but assuming it is something like cancelling.