bubble on soft pallete

About 8 months ago, during a period of dry mouth, I developed a bubble on the roof of my mouth (soft pallete area) that bothered me for a couple weeks and then vanished.  About a month ago, a similar thing appeared near the same place.  It looks very similar to a pimple, and varies in size, depending on how aggravated it is.  In the morning, it is barely noticeable and pretty flat, just a white mark.  But if I eat something like a potato chip, it can "fill up" or become swollen.  It appears to be fluid filled and even looks like it has a cream colored head to it.  I've tried to pop it, but to no avail, and I usually just aggravate it more.  Some days it looks like it is going to go away, and then it swells up again.  It's not very big, only the size of a large pimple.  Should I be concerned?

[Matthew Baron, D.M.D.]

It sounds like some kind of small infection.  Possibly a foreign body lodged, or blocked  minor salivary gland, or could even be tooth related.   You should have it looked at by a dentist or an oral surgeon to see if any treatment is required.