Hi, I'd like to help you with your question.
If you are feeling this upset by your symptoms, you definitely need to see another doctor just to rule out any possible cancer or other diagnosis and set your mind at ease.
If the doctor is able to rule out anything that is wrong physically, consider seeing a therapist if you feel that your sister's death affected you to the point where you are going to worry about your health consistently. Sometimes when we lose someone unexpectedly or when someone young dies, it can cause a stress reaction. You can also develop fears and anxiety as a result. Also consider if you feel you are still grieving. That can cause reactions such as yours, as well.
I hope this has helped you,Kate
So far, you have seen two doctors. That is definitely within reason, especially in your situation. If you feel one to two more might do it, then go ahead. Then you will have had three or four doctors opinions. That might be enough for you. If not, then consider seeing a therapist. You need to work on how these feelings you have now might be connected to your sister's death.
Keep in mind that most people with hypochondria are usually completely convinced they have a disease or illness, they do not express doubts, like you are doing. So if you are concerned, see another doctor. With your family history, there is nothing wrong with being sure. However, the stress you are experiencing and the stress for your family may be helped by talking with a therapist, regardless of how your physical situation turns out.
My best to you,Kate