What Causes Frequent Heart Palpitations And BP Alternating From High To Low?

Hello my daughter has heart palpatations frequently and occasional high and then low blood pressure. She has also nosebleeds. She works extremely hard and has a stressful personality always worrying althought she doesnt have to worry as she has a great job and no marriage or kids. She has been having stomach problems but I put that down to a bit too much alcohol over the years and too much sushi, her diet is much better now and her stomach is getting better although she cant tolerate alcohol without it upsetting her stomach as does chocolate and carbs? I am at my wits end to know what exactly it is she is suffering from. She is a responsible person does not take any drugs, exercises regularly and is normal in every other way.