Synthroid and chronic fatique

i've been on synthroid for 9 years. started at some low dose and gradually went up to112 mg. get extreme itching all day everyday if i don't take allegra for that.not a rash just itching. that doesn't bother me as much as the fatique. every joint in my body aches all the time. sure there are better days but fo rthe most part it's bad. tried physical therapy and chiripratic care but no avail. they ended my sessions. my legs get sooo weak and my feet burn lower back really aches. sometimes muscle cramps. i'm very negative towards my loving family and it hurts me to do so. can't seem to keep upbeat. soo tired all the time.
is it the syntroid? i used to be very energenic and a doer. now i have spurts of activity in the morning , but then i just can't get motivated. help me any suggestions?