Ds is 4 months, and in the last week or so he h...

Ds is 4 months, and in the last week or so he has been seriously fussy at my boobs and just generally fart arsing around. He keeps pulling off getting back on, arms and legs going everywhere, his latch isn't very good it's not causing me sore nipples or anything but I get him on and he pulls off so it's just my nipple in his mouth. He doesn't seem to open his mouth as big anymore. I've changed dummies to the next size cuz I thought that might be an issue but it doesn't seem to have done anything. Sometimes I have to just hold him real tight so that he can't move just so he will drink something, but that makes him fight even more! I normally feed him in the football position, and I have just got the hang on having him across my front, so I change positions throughout and see if it makes it any better and it doesn't! He is really driving me crazy, and it's so frustrating trying to feed him. I'm not worried about him not getting enough as I am demand feeding and he just had his check up and is growing perfect. But my boobs aren't getting drained and I don't know if that will cause problems? Has anyone been through this? Do you know why he is doing it? Will he get over it? I'm just getting frustrated when I have to feed him cuz I know it's going to be a fight to keep him on!