She's too young to cry-it-out--proponents of that method say 6 months. But personally, I think it's always too early. When they can't talk to tell you that they are afraid or lonely, I think it's pretty mean to abandon them. But, that's just my opinion.
Anyway, sleeping through the night often comes and goes. It's also not always associated with hunger. My son gave up night nursing at 8 months, but he still woke several times a night until he was almost 2. Most of the time, a pat on the back would reassure him that we were close by.
4 months is a typical growth spurt time. If it's a growth spurt, she may go back to sleeping through in a week. But then it will be teething, or learning to stand up and not knowing how to get back down, or a lost pacifier, or, or, or.
Babies sleep differently. They never sleep as deeply as we do, so anything that isn't right to their minds can wake them up.
My solution was to go to bed when I put ds to bed. That way, I'd get an uninterrupted block of 4 hours before he woke. If I had that, I could manage quite well, even if the rest of the night was interrupted. And if you don't think it's hunger, get your husband involved. Tell him what to watch for in the way of hunger cues so he can come get you if baby is hungry, but if all she needs is a cuddle, he can do that, too.