Laughing one moment then crying the next is a possible symptom of a psych problem?

Possible. It is a possible symptom if it is going on for a while. Evaluation by a psychiatrist is required.
Emotional lability. You will be surprised by my answer. Our emotions are generated in the lower part of the brain known as the limbic system. A mild degree of oxidative stress in this system makes it very reactive. Thus the emotions are normal but grossly exaggerated. Please see my blog "oxygen, the spark of life" stop all forms of sugar!