Conrad Hilton pled not guilty Thursday to violating a restraining order by showing up at his ex-girlfriend's doorstep ... but the bigger news is that he seems to be doing a lot better after getting some serious professional help.

We got Conrad and his attorney, Bob Shapiro, leaving court, and Bob says his client has successfully completed his treatment at Menninger hospital. Conrad chimes in and talks about his current state.

As we reported ... Conrad paid a late-night visit to E.G. Daily's house last month and got too close to E.G.'s daughter, Hunter. When cops showed up Conrad got homophobic.

A judge released Conrad on the condition he undergo treatment at a facility in Houston. Looks like it's mission accomplished.