It really makes me mad when I hear about doctors focusing on one thing about a person and dismissing anything else that could possibly be wrong with them. It mostly happens to overweight people and people with depression. It's like they can't possibly have anything else wrong with them that isn't related to that.
Sorry, just had to rant for a second. I'm better now.
Did they do an abdominal ultrasound? If not, they need to. It sounds like you may be having gallbladder attacks. Do you notice that the pain is worse after you eat, especially a fatty meal? Does it hurt to press below your ribs on the right side? You already said you had nausea, which also fits. It also sounds like you have a fever, which indicates an infection. It could also be a lung infection, so ask for a chest x-ray or a chest CT on top of the abdominal ultrasound and blood tests. Make sure they also check your kidneys.
You need to go back to your doctor right away and insist that he take your symptoms seriously. Don't let him dismiss you, shame you, or anything because of your weight. You are in charge of your own health care. You pay him, remember that. Be nice, but firm. Tell him that you are really concerned that it is something else and even if it is because of your weight, that doesn't mean that it's not serious or that there isn't something that can be done.
You said you were afraid of having a miscarriage? So you're pregnant? If that's the case, I think it's especially unconscionable that the doctors would dismiss a pregnant woman complaining of chest pains.
Good luck to both of you. Please write back and tell us how things turned out.