You've been given great information and advice from our members. Unfortunately, what you are going through is not uncommon. It is very frustrating and demeaning, but not uncommon.
Exactly what lab tests did your doctor's say were negative for Lupus? You have a right to have a copy of your lab tests and their results. Perhaps if we knew which ones were run, we might be able to assist you a little more. As other members have mentioned, there are some lab results that can be negative and you still can have the disease (and vice versa).
Don't give up and don't allow doctors to dismiss you. Your symptoms are very real and should not be ignored. Insist that they continue to test you until you have answers. As for the rheumatologist who says he does not need to see you anymore, you would NOT want him as your doctor if you were diagnosed. Seek another, more competent, rheumatologist; one who is willing to find out exactly what is going on with you and willing to treat you accordingly.
I wish you the very best...we are here to help you in any way that we can.
Peace and Blessings
Look For The Good and Praise It!