Should I be worried about these white spots on my gums?

[finnboi]

About an week ago, I found these white spots and tiny little bumps on my gums. They don't hurt, but they are little dry. I tried to wash it off, but it wouldn't come off, but after I woke up next morning from day I found them, it looks like it has gotten bit smaller and paler (I don't mean more white). My own dentist said it most likely is nothing serious and is maybe flu related (I had flu 1 week ago and have still little bit) or fungus. I'm still not sure what to think. Now after waking up this morning, it looks to my eyes that it has spread to backer of my gums and looks ever whiter. Could this leukoplakia or possibly even mouth cancer? Or is it like the other doctor said (nothing serious)? Should I be worried? Should I book appoitment to another dentist?

Pic from day I found them:
https://ibb.co/C8jL3Xy

Pic I took today:
https://ibb.co/QNMGLPt

[finnboi]

More info:

I went to dentist last Thursday.

Also, white patches don't feel really anything different to rest of the gums, except little dry than rest of gums.