Please help...Stress or ?? (best answer)?

I'm under so much stress atm. Just had a scare at the ER it was kidney stones, my papaw is sick with pancreatic cancer, there is just alot going on atm. I'm constantly worrying about everything. For the past 4 days Ive had this heavy feeling on my chest and at times i can feel my heart beating. When I was younger I had this same issue and the doctor told me it is stress related. How do I know if it's stress this time or something worse? I'm 21/F. Please any help or advice.