Arthur Aidala -- Weinstein's attorney -- tells TMZ his client's now in Bellevue Hospital in Manhattan after doctors on Rikers Island examined him. Weinstein was turned over to Rikers from an upstate prison pursuant to the appeal ruling.

The doctors sent him to Bellevue for more tests, Aidala says ... adding Weinstein's health is a bit of a "train wreck."

Aidala says he's spoken with Havey since his release from an upstate prison ... and, he's in good spirits and happy with his medical care.

While AA didn't specify what health issues Harvey's hospitalized with, his struggles are well-documented. Weinstein's reportedly dealing with cardiac issues, diabetes, sleep apnea and eye problems, among other ailments.

After a Los Angeles judge sentenced Weinstein to 16 years in prison, his rep Juda Engelmayer called the sentence cruel because of his age and health -- implying he might not live to see freedom.

Of course, Weinstein's convictions in New York were overturned by an appeals court earlier this week ... but, Harvey remained in custody because the overturned conviction didn't affect his Los Angeles sentence. The New York City D.A.'s office says it will retry him.