I am sick of being sick

You sometimes have to stand up to them and put them back in their place. When my oldest son starts that crap with me, I walk away and tell him to do it himself. I'm done...
He usually comes back after cooling off and apologizes later. I usually make him wait a day before getting back to the garage to help him so he realizes that he just wasted my very limited time.

When he gets really bad, I go off and tell him, "'There is the front door. You are over 18 and can go live on your own. Buy your own car, pay for your own gas, your own insurance, food, roof over your head, utilities and everything else that I give you and then see how bad you have it here." You are an adult now, and I do not have to take care of you by law anymore. If you think that you can do better on your own, go on and see how "easy" it is. Then I either leave the house, or go to my bedroom and close my door for privacy so I can cool off. He usually cools off and apologizes later.

You can't let the kids push you around. Then you loose control. You have to call them out and put them in their place to realize how much you do for them and they should appreciate it, not resent it or demand more.

My son sounds somewhat similiar to your daughter. 20 years old, last two semesters in high school pulled a 3.9 gpa, graduated a semester early, went to trade school for automotive technician and graduated with 3.9 gpa, and is now starting college to pursue a 4 year degree. Of course, we have tended to give him everything most of his life and he has become a little spoiled and sometimes needs to be brought down to reality.

I feel for you on the pain. I was rear ended at over 90 MPH by an 18 year old back in October 88. Walked away with severe whiplash. I still get back and neck pain periodically and take alieve to help the pain (it is over the counter). Not to mention, I could use to drop some weight. I should get back to the gym and work out regularly like I used to 5 years ago. That helped reduce the pain. But like most of us, It's hard to find the time with everything else going on.

Good luck with your daughter and your pain. Sometimes it helps to take a warm/hot shower or sit in a hot tub for a while and that can ease some of the pain.