If you are not having other physical complaint then the cluster of symptoms you are having is compatible for a depressive episode, if it occurring daily for most of the time. I have no idea about about your previous academic performance but if it is deteriorating than it is better to consult psychiatrist
as you are in a stage of carrier development and optimum functioning is very much required at this stage.
I guess you require medication as your sleep, concentration, loss of energy may create problem for you.Psychological treatment are also available in form of Cognitive behavior therapy.
Some tips that may be helpful are- Cultivate supportive relationships(Turn to trusted friends and family members,Try to keep up with social activities even if you don’t feel like it), Challenge negative thinking (Think outside yourself,Allow yourself to be less than perfect,Socialize with positive people,Keep a “negative thought log"), Take care of yourself (Aim for 8 hours of sleep,Expose yourself to a little sunlight every day,Keep stress
in check,Practice relaxation techniques
),Get regular exercise, Eat a healthy, mood-boosting diet.
Get well soon