Open Question: little bump in the roof of the mouth. Painful when pressed. Clear.?

i dont know how i got this. today morning i ate breakfast. After that i noticed some lil pain in the roof of my mouth. I checked in the mirror and there was a little pimple like bump in the roof of my mouth. It is not coloured, it is clear.

I pressed it with my finger and it did hurt a little. Just like the kind of pain of a pimple.

Now its night time and i checked and the lump has gone smaller and the pain has gone away.

What is this bump? i am worried. Could it just be my breakfast that was too harsh or cut my mouth somehow?