Baby is one month old. This problem appeared just a couple of days ago…

Baby is one month old. This problem appeared just a couple of days ago. She started behaving very anxiously around her breast. She searches for a nipple, gets it, sucks for 3 seconds, lets go, starts crying, wriggling, fussing. I give her breast again, the story repeats itself. She's acting hungry, takes the breast again and cries again. What could this be?