Hello again Craig and thanks for waiting.
I have worked out an answer for you, please read it through and see what you think, ... lets get started.
1. Well with Tilly's breeding yes it could well be a kneecap problem but if it all started after a fall then other diagnosis would certainly be possible. All you can do as far as diagnosis goes is to wait until you get ashore to have your vet examine her I am afraid.
2. What to do in the meantime? : The best thing to do is to encourage her to rest and keep immobile as much as possible, just keep her calm comfortable and reassured.
As far as human over the counter pain killers go your only real option would be aspirin, many of the others are not suitable for dogs and can cause problems and aspirin is sometimes prescribed for dogs.
A typical dose rate for aspirin in the dog would be 5 mg per pound of your dog's body weight twice daily.
Here is a link to a an accurate web page with all the facts you might need including contraindications : LINK
I hope I have covered your question fully enough but if you would like further clarification or to talk things over a bit more then I will be on-line for the next hour or so and I will be more than pleased to continue working with you.