head to an uncircumcised

hey ladies so I don’t give my boyfriend head much I have done it about 3 times and the third time I did it he said it hurt so I had to stop and I haven’t even tried again ever since. I’m curios to know if it is because he is uncut or would a dry mouth make it hurt? Because I was pretty badly dehydrated and my mouth was really dry. So do you think if I did it again it wouldnt hurt? Thankyou