hi hun my DD has been doing this and th CHN put it down to teething. she is doing exactly the same, shes arching her back and will chew and suck on anything cept bottles. she usually has 5 x 180ml bottles and im sturggling to get 100ml each time into her.
also how many bottles r ugiving your DD a day? 240 sounds like a lot i think up to 6 months the tin says 210 per feed but would more likely be 180ml.