Many people have expressed this reaction to antibiotics. One theory is the increasing evidence of the essential connection between beneficial organisms that we think of in regards to the immune system and digestion but that also profoundly determine our emotional state as well. Antibiotics kill off these organisms, and sometimes the body can't recolonize them afterward. But that's just a theory. It won't hurt you to take a good probiotic from the refrigerated section of the best local health food store and see if it helps, but if it was the antibiotic, it will probably go away with time, but if you imprint the feelings and expect them to continue, they will, and then it's time to see a therapist no matter how the problem started.
Everyone has different experiences with meds so you will not get the same effect. You can get a better idea of your situation if you ask your pharmacist or the person who prescribed it, since they have the background.