benefiber

I have been on syn. for 7yrs. due to graves treated with rai.lately my tsh was too suppressed so have been changing meds last time it went too far my tsh went up to 6.39 which is not good for me. Now will try to hit the lower range again I take benefiber in my coffee in the morning have done so for probably a yr. I take my sny. in the morning on empty stomach for at least 45 min. but do drink my coffee with the benefiber right away, anyone know if this could be a problem? Also take prilosec in the morning after the syn. maybe 10 to 15 min. later but again have always done this even when the tsh was suppressed. I don't get it. Why would I go from tsh 0.26 to 6.39. Thanks