10 weeks and all of a sudden issues? Please Help!

doubleXlexx

         I have been breastfeeding my 10 weeks old DS since birth, no bottles ever, and he has had a pacifier since birth with no issues. Just recently, like the past week and a half he has been eating horrible! I can barely get him to stay latched for over a minute, he pulls off and gets upset. We do this for about 10 minutes and then I stick the pacifier in becuase he is upset. The only time he really eats is in the morning, it is great. I am worried that he is never getting enough, especially of the hind milk. I have been on my period for about a week and though that could be it, but would it still be affecting the milk 1-2 days after? I try to burp him, switch sides, everything, please help TIA