Hello and welcome to HCM.
Thank you for your query.
The fact that this is a recurrent presentation arises a doubt of this being the oral form of
herpes. Although, this is only an assumption and could be due to various other reasons depending on varying activity, weather, diet, etc.
I would recommend a visit to the doctor when this
blister or
white patch appears, as this would appear at a time when your immunity is at a low (due to factors like poor nutrition, lowered immunity due to weather or drugs, infections, etc.). Get screened for all sexually transmitted infections, with priority to herpes. I would first like to rule this out.
Once sexually transmitted infections have been ruled out we can move forward to examine and send tissue samples to the laboratory to find the cause.
I hope I have succeeded in providing the information you were looking for. Please feel free to write back to me for any further clarifications at: http://doctor.healthcaremagic.com/doctors/dr-shoaib-khan/64581 . I would gladly help you.
Best wishes.