Bust size growing

Hi mummies, just wanna find out the reason behind this incident I had recently. I'm 19 weeks pregnant and the other day my breast grow tremendously out of blue and I'm talking like really engorged with new stretch marks appearing. It was painful and unbearable.. but 2 days later it went back to its pregnancy size. I would've understood if it grew and stayed that way but it literally just grew and went back to normal. Please help, I'm trying to understand what this is . #advicepls #pleasehelp