Is it possible an underactive thyroid could make my carpal tunnel syndrome & raynauds phunomenom symptoms worse?

It can with CTS. Hypothyroidism can lead to fluid retention which can in turn worsen cts. Very unlikely though that the same will apply with regards to raynauds. Hope this helps.
Good question!! My research today yielded evidence that, indeed, thyroid deficiency is a risk factor for both. Here's a reference for the raynaud's: http://www.Ncbi.Nlm.Nih.Gov/pubmed/7387277.