You could always call your doctor and see what they say. If you need IV fluids and an X ray, would that be something that could be done in their office? I know different doctors have different setups.
If you have a pulse oximeter in the house, that could also give you a hint. I have trouble breathing when I am anxious, and being too stuffed up to breathe makes me anxious, so I check my blood oxygen to give me an idea of whether my issue is an emergency. 96% or above is normal for most people. If you are lower than that, that is bad.
Call someone to take you early to your appointment your doctor then can direct you to urgent care if nessecary and will have more insight then us. Tell them that you need to see the doctor immediately to advise if you should go to urgent care.
If you get sent to urgent care your doctor can try to shuffle his schedule using your slot.