My doctor prescribed "magic Mouthwash" for mouth sores. I do not swish it because it causes my entire mouth to go numb
I use q-tips and apply on individual sores.

Prednisone increase and hydrocortisone cream on the spots that's what I do

I wash my teeth with baking soda, it helps getting you more alkaline and the sores healing.

When I a flare I try to listen to my body and rest. Depending on how bad it is I will contact rheumatoid doctor and see if I need to increase steroids. I always have a lot of trouble with mouth sores and sore throat. I have nystatin for this that doesn't heal it but takes edge off. I drink plenty of water.

Thanks DanReedy