Oral mouth blister treatment?

[Surami2020]

I am currently taking 20mg leflunomide since mid November and have very little problems. Last Thursday my gums felt inflamed and today I have discovered I have large blisters on the roof of my mouth near my gums and a couple of small mouth ulcers. They aren't painful but it is making brushing my teeth difficult and I am worried about infection.

Is there any treatment to prevent them? When I was on methotrexate the folic acid was increased- will this be effective on leflunomide. I have done a google search and can't find any information to help me. TIA.