Thanks for your question, and sorry to hear about your problems. You did the right thing by speaking with your doctor
about your concerns, and I am sorry to hear that you are still having the pain. As you know, back pain during pregnancy is something that most women will experience at some point. If you did not have it during your other pregnancies, that does not mean that it is not something that will never happen to you. While there are many possible explanations, with most people, it has something to do with the extra weight and strain of the added baby weight. As for your other symptoms involving your chest and your head burning, there are also many possible explanations. Your doctor will also be able to help you understand these. It sounds as if he or she is not overly concerned about them, and so you may need to ask for some help in controlling the symptoms that are affecting your quality of life. Speaking with your doctor about your concerns is always the best place to start. Please speak with your doctor about this question, and good luck.