My 7 monts old son refuses the bottle

Hi!
I have a 7 month old son, who started refusing bottle 7 days ago.
He is more than happy to breast feed.
I tried using the sippy cup, and it worked a couple of times with
freshly expressed milk.
I noticed that my milk from fridge seem to have a very strong smell.
Is that usual?
Is it possible that this smell/taste is the reason for his bottle
refusal?
Thanks,
Maya