Hiv testing is only accurate when it's done at the three months mark-34 days to go my friend. What was your exposure? If you don't mind...
50 days test result is very encouraging. However, it's not conclusive. 3 months HIV test after possible exposure, is conclusive.
The Accurate is greather than 90% at 50 days
A conclusive test result is obtainable at 3 months post exposure.
But, still, a 50 day test is a very good indicator of your HIV status, and is very unlikely to change when you take your 12 week conclusive (according to the US CDC) test.