What's the longest your baby has gone not nursing

And I mean during the day. I feel like my little one is going on a breastfeeding strike because she doesn't want to nurse as often as she did. Last time she Nursed was around 11:30 and it's almost 3pm. And every time I latch her on she sucks for about 5-10 seconds then latches off and is frustrated. Once milk comes in she does the same thing. It takes me 5-6 tries to get her to nurse and then eventually she'll nurse and empty the breast. Not sure what's going on. Please help! Should I be concerned and cal her doctor?