My girlfriend has a severe headache with left arm pain/fatigue. is she having a heart attack, stroke, or even a feminal hemiplegic migraine? she's 26 with a pre-existing heart issues ( skips a beat). what can be done to help her?

I strongly recommend she be examined at her physician's office as soon as possible, or go to an Urgent Care type of place near you and/or get the the emergency room if these symptoms are constant or getting worse. As quickly as possible. Even if it turns out not to be an emergency, at least she may be able to get some relief instead of suffering and being frightened.

if this is a recurring/frequent problem/attacks, it is likely complicated/neurologic migraine. Heart attack can occur but not that often at 26. skipped-beats are quite common and by itself not consider heart disease. I strongly recommend seeing doc for evaluation--he/she can check for heart concerns, and likely will be able to help with the headaches--heart attack should not cause headache.

Unlikely that any of this represents heart disease, and instead of guessing, she needs to see a neurologist. The left arm pain may be referred from neck or brachial plexus, and either can trigger a headache. Whether she has migraine is unclear from your post. Get proactive and find answers and appropriate therapeutic interventions.