Hi Courtney,
Orabase forms a seal over the sore where Orajel just numbs it for 5 minutes. Orabase does work pretty good...funny I never thought about using that.
That's a shame about the viscous lidocaine, that helped me. I found it helpful if I put it on my finger and rubbed it right on my tongue. I'm sure you tried this but if not, give it a whirl. I really hope something works for your sister. I know how FRUSTRATING that pain can be. I cringe just thinking about it.
It warms my heart to see sisters. My older sister has been so amazing, I could not get through this without her. I'm sure your sister feels the same way.