Canker sores?!?!

About 3 weeks ago I noticed that in the back of my throat there was bumps there,and the top of my mouth is white.. I searched and seen about canker sores and I don't know if it is. I went to the doctor and he said the thing in the back of my throat was red but there's no infection,I told him about the bumps in the back of my throat and he looked and said nothing.. There still there after 3 weeks and I always panic because I also have a panic disorder,he didn't take me seriously! I can see them when I shine my phone light there but the light he was using was dull!! Did anyone else have this??