Tongue Sore

I recently started using crest mouth wash 3-4 days ago and my tongue got sore.  Now on the right side of the mouth closer to the back molars, there is a slightly white "sore" on my tongue.  When I touch it it seems to have a little hard spot but I cant really tell.  Is this probably a canker sore or do I really need to have it checked out?

Thanks

[Mahan787]

It may not be necessarily cancer.
But u need to keep an eye on it.Sores/ulcers which are with white and red colour(patches) and those which are not healed automatically in 3-4 weeks are need to be followed up. Goto a dentist and check with him if u wanted to find out ASAP.Some times vitamin difficiencies also cause such kind of sores.