Hi.. Thanks for the query.. A sore over the lip that seems inflamed leading to increase in size and swelling can be an Apthous Ulcer or Canker Sore that might have happened due to traumatic injury like lip biting or due to any equipment if placed in the mouth during hospitalization.... At times a Canker Sore can be due to side effects of any Medication or at times can be without any specific cause.. So my suggestion is that she can first get the sore clinically evaluated to rule out the exact cause although it does not seem related to stroke.. As of now apply numbing gel over it and do cool compresses. Hope this helps.. Regards..