I've been feeling really happy and then the slightest thing can make me angry and depressed. help please?

How long?: No individual advice - consult a professional. In general, it is normal not to feel the same all the time, but extreme mood swings if they last very long or cycle can be a consequence of medical or psychiatric disorders. Some individuals may have what we call smiling depressions, or other mays reflect rapid or more slowly cyclic mood disorder. Consult a psychiatrist or psychologist or your doc.

Mood changes: Recommend evaluation by a psychiatrist for your rapid cycling moods, to provide proper diagnosis & recommend treatment. Also, medical workup is recommended to rule out other medical causes or effects of hormonal changes. Good luck.