Ana has been negative, but a rash biopsy was suggestive of a connective tissue disease. rash on chest, appears in winter. anything to do but wait?

ANA testing: There is a rather large cluster of poorly defined illness known as mixed connective tissue disease in contrast to the classic ana+ diseases like lupus, arteritis, etc. In these the ANA may not be positive, and biopsies of affected tissue may be abnormal but not diagnostic. As you surmised, in these cases really the thing to do is wait since a trial of treatment may have significant side effects.