23 y/o f. for about a week i've had mild chest pain on and off on left side. jaw started hurting a few days ago, and headache. could it be serious?

Chestpain: This all sounds muscular to me, are you under a lot of stress, you may be developing TMJ pain that can cause jaw pain and headache.

Possible: Although risk of coronary disease is lower in a 23 year old female, it is not impossible. With progression of symptoms, prompt evaluation is recommended.

Go see your Dr and: Have an ekg done to screen for heart disease. If it's abnormal, further testing is required- echo and stress test. Generally chest pain in young people is usually related to musculoskeletal and stress or anxiety unless there's a strong family history of heart disease. Only your dr can give u an accurate diagnosis.Take care! http://heartdisease.About.Com/cs/coronarydisease/a/cp1.Htm.