ive been taking phentermine for about a year on and off i lost about 40 lbs,but for the past few months ive been very emotional, depressed, exhausted and its becoming very hard to keep the weight off especially in the mid section. also my muscles are in a lot of pain all the time,my lower back hurts so bad when i wake up in the morning i can barely get out of bed and im only 25.does anyone think my problems could be related to phentermine.