I have a 9 year old golden retriever. The top of her head suddenly feels really hot, I am not sure waht that means?
Dogs frequently feel hot to humans due to having a normal body temperature of 101-102.5. If your dog is eating, drinking, eliminating and other wise fine, your dog may have had her head near a heat source such as a heat register, oven, etc. If there is swelling in the area, which you do not mention, it may indicate an infection. To be sure, you can take a dog's temperature by applying KY jelly to a thermometer and inserting it approximately 1 inch into the anus. If using a digital thermometer wait until it beeps to read it, otherwise leave it for a full minute before reading. A dog's temperature is 101-102.5F.
If your dog's temperature is over 103F, your dog has a fever and needs to be seen by a Vet.
You could use vasoline, or mineral oil. It is just to make it easier to insert and cause less discomfort to your dog.