thank you ny2 for your concern and reply.

yes i have researched about the medical visa but it will be too much to cover, i mean i will not be able to get an approximate cost because till now the doctors are not able to locate the system which is affected, hence i don't know whom to consult in US. My idea is to come there and meet the physician show him my reports and get the advice on the diagnosis. As i have insurance here and any medication prescribed in US is available here so will carry on with the treatment here.

Can you provide me the advice on what will be the best reason to get tourist visa? i have a good job here, and income is quiet good. and they will write any kind of letter to consulate like vacation, work bonus, official tour, etc. so that i can get the visa.