Jeremy Lin Recovering Well After Scary Head Injury, 'No Long-Term Issues'

Amazing news ... Jeremy Lin says despite the horrifying head injury he suffered during a basketball game on Sunday, he's now doing OK -- and expects to make a complete recovery soon.

The ex-NBA star provided the awesome update in a video on his Instagram page Wednesday ... saying after undergoing a battery of tests and imaging this week, docs have told him he'll have "no long-term issues" following the scary concussion he sustained just three days ago.

In fact, the 34-year-old said he'll be cleared to hoop again in two-to-four weeks.

"I'm on the mend," he said.

Lin was initially hurt during a Taiwan P. League+ game over the weekend ... when he took an elbow to the face and then smacked his head on the hardwood as he fell to the ground.

The play was horrifying -- Lin's body appeared to have a fencing response to the blow. He was then ushered to the hospital, but, thankfully, he was discharged and able to return to the arena to root on his team.

Lin joked about the entire saga on his IG page -- writing, "As one of loved ones reminded me today, there werent too many brain cells to begin with lol."