The white patch
could be many things. Most likely it is not a parasite like a tapeworm. It is more likely to be a wound from trauma Or fungal/bacterial/viral infection. If it heals within 2 weeks and does not recur or spread, then you are in the clear. If it recurs/spreads/remains over 2weeks, then have a dentist
or oral surgeon consult. First off, does it wipe off; if so, then it may be associated with a fungal or yeast build up/infection. Next, if it does not wipe off; then it may be viral/bacterial or trauma. The main option is get a dentist to look at it if it lasts longer than 2 weeks.