I Am A 59 Year Old Male And Have Had

I am a 59 year old male and have had sinusitis problems for weeks ..I have been taking claritan d 12 hour tabs twice a day for over a week now. My sinus problem is better but 2 days ago I woke up with a rash in the roof of my mouth and some spots on my tongue. These are white spots and my mouth feels sore. Could it be the medicine claritan d that is doing it? Never had any trouble taking it before. Thanks.