I have 16 day old ID twin boys, that were born at 36 weeks. I am combining beast and bottle. And also expressing milk as they have had difficulty latching on.... anyway
The smaller twin seems to struggle with being REALLY uncomfortable after feeding, We are giving him 90 mils roughly and he takes on average about 50 a time (give or take) sometimes he will take the full 90 mils.....he is 5lb 1 oz. We are feeding them every 3 hours, at the moment waking them up for feeds. I have been told that until they start to put on weight (which they have done in the last two weeks...) I am to push as much food as possible. Because they were premature I seem to be obsessed with the amount of food and weight that they need to have / put on..... 
I get really upset feeding the smaller one... he really seems uncomfortable and just cant take it.... He sounds like he is in pain.(he wriggles around and makes these sounds like he is in pain) although he NEVER crys ..... but sometimes he goes purple around the mouth...which would indicate wind Ive been told....
we spend AGES winding him, and have invested in Dr Browns bottles.... but this really doesnt seem to make much difference.
My DP and I are finding it really upsetting.... What makes it worse is that his brother wakes every 3 hours, feeds like a dream and winds all within a couple of minutes...... and the smaller one is struggling.... And his brother really is quite a bit bigger.
I just wish that I could take what would appear to be his pain away everytime....
I really DO NOT want to start using any form of medication to help him like gripe water...I dont like taking anything myself....
Does anyone have any advice for me.... Its also probably new parent anxiety as well.....
Any advice will be greatly appreciated. Thank you.