Your best bet is to go see a therapies. And follow up with a doctor all injuries are unique in the way they heal. You can also go to your local library an ask for books on running injuries that may help.
parasites?
injuries to the skin heal faster than injuries in the brain because of cell division. When your skin cuts it heals faster then when something happens to your brain because your skin cells wear out quickly, so they need to be replaced often. That's why it is faster to heal than injuries to the brain :)
Injuries in the brain do not heal because brain cells cannot grow back. On the other hand body cells (skin) do grow back.
Bone injuries heal very quickly because bone has a lot of direct blood flow. This direct blood flow delivers the nutrients needed to heal an injury.
No, they will eventually heal.
Emedicinehealth.com is a good place for information regarding running injuries. Injuries from running may include ankle sprains, turf toe, and a knee strain. Serious injuries from running are uncommon but a ruptured Achilles tendon or stress fracture can result.
I don't think this is a good idea, running with a hip replacement might even damage the muscles, she should do some walking charity event instead of running.
Because they have a greater blood supply
Platelets
The neurons in the brain and else where do not normally regenerate. Skin cells do regenerate.
You would have to ask a jogger or a person who runs. You can also visit a website on running injuries to find out which were the top 5 reported injuries that are common.