While he certainly could have been more delicate with how he said it, I think your husband sees what we all see - that the problem lies with your health anxiety and social phobia, not with your son.
Having crippling phobias and anxieties is nothing to be ashamed of, though now that you know how they are negatively impacting not only your own life, but the life of your son, will you please talk to your psych about it? Tell your husband that you are going to talk it over with your psych and that you need his support, not criticisms. It is his son as well as yours. Then, take your son to the doctor asap even if you have to make an emergency appointment, tell him/her your fears, and get him/her to examine your son.
Above all, do something, even if you find it hard or scary, do it for your child.