Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
As per your complain you does not seems to be suffering from
thrush while you seems to be suffering from inflammation of the oral mucosal surfaces of mouth and the condition is known as
STOMATITIS..
Wearing snore guard can be one of the cause in case if it does not fit well or it can be due to other conditions like Nutritional deficiency[
vitamin B12,
folic acid etc],
dry mouth etc..
Oral infections like thrush also causes it but in case if there is no white coating, chances are minimal as well as semen or sperms does not cause it..
Nothing to worry consult an Oral Physician and get evaluated and treatment can be planned according to the cause..
As of now do gargles with cold water..
Sucking ice pops can also help..
Avoid hot , spicy and hard foods.
Get the snore guard checked for its fit or any sharp or rough areas and if found get them corrected..
Hope this information helps..
Thanks and regards..
Dr.Honey Nandwani Arora.