PMS or something else?

These two months is entirely erratic, my moods fluctuates up and down with no pattern. One minute I am ok and fine, and the next I'm angsty and feels like dying or something. One moment I smile and laugh, the next I'm feeling hysterical and feels like breaking down in tears or having a meltdown by screaming/yelling at nothing and absolutely everything.

It really really makes me question my sanity if nothing else... to top it off with the stress that comes in from work... it's a miracle that it haven't drove me to the point of needing a shrink.