I seem to be having sores in my mouth. they are whitish in color, but really dont hurt, not experio

I all of a sudden have sores in my mouth.  Maybe I'm too worried.  I dont have anything geneticaaly, and no breakouts on body at all.  The outbreak is stricylu to he mouth.  One on top of tougn, one underneath tongue, and on side of my mouth, there arearea of my mouth in the back that have a horizontal 3/4" white sore.  Abit on the other side too.  I am very scared.  I do take effexor, and 2 other anti depressants, but have been taking these drugs for a long period of time with no probles.  Is herpes usually on theoutside of the mouth or inside?  No symptoms in vaginal area in any other area.  Was in a new relationship, and he swears he oesn't have herpes.  I gave him oral sex, and the next day,  my whole mouth was sore, I though it was thrush,and took the appropriate medication, I thought, first it was whitish sore tongue, now there a few specific unpainful sores happening in my mouth.  I'm very worried, and could use some advice, please.