Are you able to post a photo of the swollen foot? It sounds like all her symptoms are related to that. We like to think they are so attached to us that they would be depressed when we (or your daughter) are not around but really, that is unlikely. If a pig is not eating it is often from some time of illness. If there is swelling there most likley and infection is going on. She may have a hoof abscess.
If you have a vet you use you should really have them out to examine her. It is very difficult for me to give much advice without seeing her or examining her myself. I can only guess based on the information you give me. So, I would have your vet examine her for sure. Lila likely needs to be sedated to get her hooves trimmed properly and to check for an abscess.
In the meantime I can give you some ideas that may help her.
1. Soak the foot in warm Epsom salt water, 10 minutes 3 times per day. If there is an abscess present that may help to draw it out.
2. Keep her in a VERY dry area. Any moisture will make the abscess worse.
3. You can give her aspirin but I would only give one dose until the vet comes out. You don't want to mask any signs but at least this way she can get some relief. Use BUFFERED aspirin, 5mg per pound of body weight given with food. Example: if she is 70 pounds she would need 350mg; the buffered aspirin is 325mg so I would give her one tablet. You will need to round to the nearest 1/4 tablet as it will be hard to get an exact dose. If she is in between doses I would suggest you go lower, not higher. If you need help with dosing let me know.