Hi, I am Dr. Peter and would like to help.
1- How long ago did she eat the grease?
2- How is she walking?
3- Is she vomiting?
4- How long has this been going on?
1- Can you describe how is she walking?
2- Can she get it up?
3- Can she go upstairs?
This could be related to ingestion of the grease and causing a bought of pancreatitis. Or, it may not be related to the grease and she may be having some musculoskeletal pain. There is not much you will be able to do for her at home; I would recommend that you take her to ER vet, both conditions mentioned above do better when we get to them early. If you are not able to get her to a vet, then, do not feed her during the next 24 hours; no food or water orally. If this is related to the pancreas she cannot have anything orally. If she starts to vomit you can give her Pepcid AC 0.25 mg per pound body weight every 8-12 hours. Have her checked in the morning by your day vet; they will be able to establish difference.
If you have additional questions I will be glad to answer them.