I am a mother of a 12 year old girl with SWCAH.  When she was born I was told to give her the Cortef 3x a day with food or drink.  I gave it to her at breakfast, lunch, and supper.  Every 3 months she went into crisis. At age 2 1/2  I was told Cortef lasts 8 hours in the body. Have been in crisis 3 x since.  Talk to your doctor.  Part of your problem may be you need to change to every 8 hours.  When your kidneys are stressed blood pressure will raise.