Milk going sour too quickly

I've noticed that suddenly my EBM is going sour really quickly anybody know
why this is? The temp of the fridge is ok. The only thing I can think of
is that I'm not very well at the moment. I'm waiting to see a cardiologist
because of a very irregular heartbeat, that is making me feel really crappy
and tired all the time. I can understand this affecting my supply levels,
which it seems to have, but would it affect the quality of m milk as well?

TIA

Ellie

DD & DS almost 6 months old!! )