I would say yes, you most definitely should see a psychologist of some sort. Therapists are not so terribly expensive that it would set you back a whole lot more than a doctors visit. You could likely get away skimping on the recommendation from your general practitioner as well with some research--could save you some cash.
In other news, with the symptoms you provided, it does sound as though it would be a form of depression, possibly a depressive episode. The lack of concentration, ambition, and irritability are hallmarks of such things. Not to say it is a disorder, as that implies that it is long standing, which it may or may not be, not a whole lot of information was provided, and for fair enough reasons. You could stand for some CBT (cognitive-behavioral therapy).
To me, it seems as though you have maladaptive behaviors, coupled with the breakup which turned your focus to them, making you more aware of it. Nothing that can't be fixed, nor anything that is terribly serious.
As for smelltheglove, you are actually backwards. A psychiatrist is allowed to prescribe medication, and typically does so coupled with some sort of therapeutic technique. Psychologists, on the other hand, are not allowed to prescribe medication without recommendation and input from a psychiatrist. Psychologists typically stick to therapeutic approaches, talk therapy, for example.
As for your "maladaptive behaviors," as I called them, they could be caused by various things--relationships, the way you were raised, inefficient coping strategies, you name it, it's possible. I would recommend seeking therapy if that is what you are comfortable with. Diagnosis cannot be given without it being disturbing to yourself or others, providing some form of danger, be it to yourself or others, deviant from the norms of society, and dysfunctional enough to become a problem in the first place. To me, it sounds like you meet all of the above criteria, with the exception of danger, which you hadn't alluded to. Mind you, they can still treat you, and give therapy, but not diagnose you with a disorder without those criteria met.
The other thing you need to be wary about, as I have read some of your posts as I was typing this-- to be qualified as "depressed" you don't need to meet every symptom, only five of them. While you are right, you aren't necessarily in a position to evaluate yourself, you also should discredit other evaluations. Just from what you said, and a minor amount of extrapolation, you met 4 of the 5 criteria for a major depressive episode, and that wasn't even touching the physical effects, such as sadness, or psychomotor abilities. You could very well qualify as having a major depressive episode. For further diagnoses, use the DSM IV, or V, depending on when you get around to it. Their website contains much of the information used to diagnose someone. The DSM IV criteria for a major depressive episode is as follows:
(1) depressed mood most of the day, nearly every day, as indicated by either subjective report (e.g., feels sad or empty) or observation made by others (e.g., appears tearful). Note: In children and adolescents, can be irritable mood.
(2) markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day (as indicated by either subjective account or observation made by others)
(3) significant weight loss when not dieting or weight gain (e.g., a change of more than 5% of body weight in a month), or decrease or increase in appetite nearly every day. Note: In children, consider failure to make expected weight gains.
(4) insomnia or hypersomnia nearly every day
(5) psychomotor agitation or retardation nearly every day (observable by others, not merely subjective feelings of restlessness or being slowed down)
(6) fatigue or loss of energy nearly every day
(7) feelings of worthlessness or excessive or inappropriate guilt (which may be delusional) nearly every day (not merely self-reproach or guilt about being sick)
(8) diminished ability to think or concentrate, or indecisiveness, nearly every day (either by subjective account or as observed by others)
(9) recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide
(Master's psychology student (social psychology))
Edit: more information of depression/diagnosis process