You are right, many things can happen during therapy for HCV, and
severe problems are rare, they can still occur.
Thyroid dysfunction is seen in around 5-10 % of all cases but is rarely
severe. It is much worse if the patient remains hyperthyroid after IFN is
discontinued. The majority of the hypothyroid cases are easily managed with
thyroid hormone replacement.
Having said that, your case is unusually severe. You mention that you have
articular symptoms also, and all can be explained by the immunologic
etiologies (causes) of both thyroid and arthritis in HCV. You may benefit by
complete evaluation by rheumatologist, as therapy with immune modulators can
help both types of symptoms. You will need also to have work up for other
immune diseases, and treatment as needed.
Regarding the therapy with analgesics, your doctor should not be as
to use them, as only in very high doses or in specific patient indiosyncracy
you may have problems. More important that analgesics, is to try decrease
inflamatory process as we described