Periods
What is pms exactly?
PMS is a cluster of physical and emotional symptoms in the week before a period that settle once bleeding starts. A more severe, disabling form is called PMDD, and it is a recognised condition with specific treatments. Both are hormonal, and neither is a personality weakness.
What this does and does not tell you
This is general information, not a diagnosis. Only a clinician can examine you, take your history and run tests. The same symptom has different causes in different people.
If something is sudden, severe, or getting worse quickly, get medical advice rather than reading on.