I Recently Developed A Canker Sore Way Down Underneath My

I recently developed a canker sore way down underneath my tongue near my right limph node causing me to feel like having a sore throat. ...I've been also suffering from alergies which has prompted me to use Flonase now I have hard dry skin inside both my nostrils sore to the touch and just wondering why dies this happen and why do I get canker sores often?