4 month old teething

My 41/2 month old he is teething and I don’t mind nursing him for his naps and to go to bed but he gets so frustrated when he gets on my boob because he wants to go to sleep like I’m a pacifier on my boob but gets upset with milk is coming out . When he eats he will eat from my boob no problem because I thought he was being fussy because my flow was coming out heavy or fast but he even fussy on my slacker boob. I hate having him cry his self in my arms for nap time it’s sucks I don’t know what to do to help him 😩