Hi Lee and Ruby,
I can sympathize with your situations. DS would screem, wince, arch his back, and generally fight during a feed. The first 7 weeks were 'hell'. Like your LO's DS continued to gain weight (by leaps and bounds actually) but mealtime was a nightmare. Have either of you read the Reflux 101 post in the Colic, Reflux & Crying forum? I checked off all of the 'symptoms' that DS had and then went into my doctors armed with the information. At first they wanted to do nothing, but I persisted, I wanted something done and was determined that they would do something.
In the meantime, if you suspect reflux may be your culprit try elevating their matresses and change table pads. Be sure that after they eat, they 'sit upright' for about 20 minutes afterwards. I hated to do this because we had to feed more frequently, but smaller meals also helped.
I wish you both the best of luck. I remember how stressful those times could be.