If your concerned about a child with a specific condition, you may find it useful to get in contact with a relevant support group or organisation. They may not be able to provide indivdual medical advice but can provide some general guidance about particular conditions.
If your child is vulnerable and needs to self isolate for a period of time, plan and prepare as best you can. Make sure you have adequate medicine supplies and people who can help you in an emergency.
You can use this link for further information.
Latest Government advice on caring for a child with additional needs during the outbreak:
Coronavirus (COVID-19): guidance for care staff supporting adults with learning disabilities and autistic adults