Question about Dentists and ?

I recently began going to the dentist because I just git my insurance back. About two days after my first appointment I noticed a pimple like blister on the inside of my cheek, I didn't think anything of it because I had had little pimple like things before (probably about 3 in my life) and so i popped it and went on about my business. Within the next week however, I noticed two blister like sores on the inside of my upper lip. They are still there after 5 days. They have white heads in the centers, but they don't just pop and go away like the others I have had...Could this be or something that I could have picked up from the dentist? I noticed that it seemed a little unsanitary in the office, but I thought I was just imagining things.