Hi from PA`I need help again

[backache]

I just received a letter which informed me I have an appointment at my place of emploment in 3 days for a Independant Functional Capacity Eval. It goes on to state I should wear comfortable clothing because the evaluation will be active and last 4-5 hours. My WC DR. had put me back to work 2 days a week 4 hours a day, light duty, no lifting, bending, twisting, pulling, pushing, squatting,sedentary work only..... and I have only made it through one 4 hour shift because my co-workers picked up the slack. I now went back to my family DR. and he has me off work the next 10 days. Should I inform them since I don't think they received the notice from my employer yet that I am off for the next 10 days or should I go in, it's 20 miles to my place of employment and show them my DR. orders. The gentleman signed his name and MS, OTR/L CEAS, CMT follows it. Do I follow my DR's order or do I have to attempt to listen to this person. I am going to tell them up front, anything else happens to this back because of them and heads will roll. I am sick of their sh**. Thanks