Vinegar smell

I'm 36.5 weeks pregnant and have been having a lot more bh lately and cramping, today I noticed a vinegar smell in my underwear, which is not a typical smell for me I've also been leaking a little more today. Does anyone know what this could be from? No itching or discomfort either. I'm going to put a pad in and take my dogs for a walk to see if I leak more but don't want to worry if I don't need to. Thanks in advance!