Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Contact local emergency services or a crisis service, and stay with a trusted person if possible.
Seek urgent help if you are having thoughts of self-harm or suicide, feel unable to keep yourself safe, or believe you may act on these thoughts.
Urgent assessment is also appropriate for severe new pelvic pain, fainting, or heavy bleeding accompanied by weakness, breathlessness, or dizziness.
These are not typical PMS symptoms.
Arrange a routine appointment if symptoms repeatedly affect work, study, sleep, relationships, or usual activities.
You should also seek advice if self-care has not helped, symptoms are getting worse, or you think you may have PMDD.
Routine assessment is also appropriate if symptoms occur throughout the month, periods have changed, or you have significant pelvic pain or bleeding.
These features may have another cause and should not automatically be assumed to be PMS.
Every sign above is quoted from the sofidex article on Premenstrual syndrome. If you are not sure, err upward — it is always reasonable to be checked.