Taking a break phentermine

Why am I phentermine so tired??????.I started phentermine Wednesday and phentermine, and I felt weird but okay, Thursday I was fine, Friday I had lots of energy and today I was sleepy all day for some reason??? Has anyone felt this way? Am I doing something wrong?:(
Taking phentermine a break.I hope I made , “phentermine” the right decision. I have been on phen for 2 months. Lately I feel I am getting immune to it. Sat I was supposed to go to the dr. he gives 1 month supply. He only has these appointments every 2 weeks.