I am not sure if they are regular dreams but they may not be visitations either. My thought goes to your subconscious interfering somewhat out of concern for your dad’s soul’s well being. That is human nature to worry about a loved one recently passed over. So our minds can cause crazy things to happen in our dreams that consciously we worry about in a waking state.
I promise you your father will be perfectly fine, happy and whole again. There will be no earthly conflicts or health issues plaguing him in any way. Send him your love and thoughts and know he receives them always! Start to believe and know your father is safe and healthy and whole and when you dream of him in the future, you will have a different experience.