Hello Friend, Good that you are seeking a help here. Lack of energy, sleepy etc are symptoms of emotional disturbance in your mind. Various factors like lifestyle, stress at work, worry about past or future, relationships issues etc could influence such change in your life.
However it needs further evaluation of your both physical and mental condition and symptoms to isolate the root cause.
Be positive, it's an addressable problem by adopting few lifestyle changes or self therapies or excersise and dietary changes along with counseling.
Next Steps
Feel free to reach out to me directly or online through Practo for further detailed evaluation and suitable recommendation that you can follow practically to overcome this problem. Be positive. You will be alright soon.