Is it acid reflux?

My 6 year old daughter has had the same problem for a couple years now.  About once every couple months, she will have what she calls a "heart attack" in the middle of the night.  After about an hour or two of sleeping restlessly, she will sit up and throw up. Once she has done this, she will almost immediately fall into a much more peaceful sleep. We have noticed that she will do this more frequently after certain foods, such as pizza or spaghetti, so we have definitely limited those foods, but every once in a while it will happen even with other foods.  And even when she does not throw up, I can hear her swallowing hard all night. And now that she is in first grade and eating lunch at school, she has actually thrown up while eating her lunch at school several times.  I went to a pediatrician in the group of doctors that we take her to with my concerns, and he would not listen to me. He zeroed in on the fact that she is overweight for her age and told me that this was her only medical problem. He said instead of focusing on acid reflux, I should be working with a nutritionist. I completely understand that she should lose weight, and she is active with dance, swimming, and every day play.  I modify her diet, trying to avoid acidic foods, caffeine, etc.  I have raised the head of her bed.  I would like to talk to another pediatrician and see if I get the same reaction, but I don't want to be looking for problems.  I tried to ask him about possible damage to her esophogus, but he said "if she's not bothered by throwing up, then why are you worrying about it." He left it at working on her "obesity." I am doing everything I can to help her to lose weight, but she just threw up again last night, and I just don't want to ignore that fact that I don't think this is normal.  I don't want her to be put through a lot of unneccessary and unpleasant tests, but I am concerned.  I know I can ask for a second opinion, but I am worried if I question another doctor's opinion, I will be made to feel even worse.  I am definitely not a doctor and do not claim to have that knowledge. I just want to do what's best for my child.  Should I stick with working on her weight problem and hope that she will stop throwing up once she loses weight?