Can I Take Thyroxine For Underactive Thyroid While Suffering From Hip Pain And Back Pain?

Hi Doctor, for the past two years I have had chronic hip, leg, lower and upper back, wrist and elbow pain. Sometimes I have them all at once but I seem to continually have chronic lower back pain/hip pain. My doctor has said I have spondalethesis (I think that is how you spell it). I have had so many blood tests and always test positive to ANA but my markers are not high enough to single out anything in particular. Four days ago I had had enough and went back to the doctors again blood tests indicating the above, I asked what else could be causing these problems and he said a chronic infection. I have been for blood tests again today to check for this but my doctor has said he believes these will all come back negative and that we are looking at a rheumatology problem. I have an underactive thyroid and take Thyroxine for this. Looking forward to your thoughts, regards Michelle