I Have Been Taking Pristiq For Several Years. I Am

i have been taking pristiq for several years. i am now at 100 mg and it worked well for me for a long time. for quite a while now i have no energy and am more depressed and i have slept for as long as 13 hours at a time when i am off work and can still go to sleep at bedtime. i am considering going to the dr and asked to change to another. any suggestions as to what medication