I'm worried about my dad's health
I'm sorry to hear that. Why exactly are you worried about your dad's health?
He's stayed in bed for days! I'm worried he has a serious illness.
It's good to be concerned about the health of one's parent as family members are supposed to care for one another. If your dad hasn't got out of bed in days, it would be a good idea to contact a medical professional to diagnose what is going on with his health and get him the treatment that he needs.
It's not that simple! He hates doctors and he'll never agree to see one!
I wonder why you father hates doctors. Perhaps he had a bad experience. You should try to help him understand that getting checked by a doctor is a good thing, tell your dad how important his health is to you.