I have a two month old daughter who is usually so quiet, calm, alert and full of smiles but won't stop crying or fussing for some reason tonight.

I've changed her, she had a b/m

Burped her 3 times (she usually does on her own)

Tried feeding her, she quiets for a few then

grunts and fusses at my breast detaching then reattaching

Checked for white patches in her mouth

I checked to see if she was too hot or too cold because our a/c is on

The house is completely dark

I took her for a walk along the track out back

Put on her favorite movie work for 10 min then back to tears

None of these things has soothed her, I don't understand she was fine earlier and shes too young to be teething.

What else could it be or can I help sooth her, its been 3 hours now?😩