Girls, who have had this, in one and the same time at lunchtime and before…

Girls, who have had this, in one and the same time at lunchtime and before bedtime the baby starts on hands when I feed him as if he's arching or straightening up with a squirm immediately turns red and starts not to cry for a while then throws it back and takes it again and so on repeats until you calm down? Weight is gaining well, breastfeeding exclusively, what could it be, can you tell me?