I was there all over again

I just had my first flashback in about 18 years.  It was NOT pleasant.  My daughter came into my room and found me bathed in sweat and shaking a little.  She was scared out of her wits.  So was I.  Why is this happening now???  It has been YEARS since those dark times.  I am REALLY trying to understand.  Tomorrow, I go to the VA and I just do not want any drugs.