Instagram / @cheetah

Tyreek Hill 's eight-month-old daughter was taken to the emergency room on Wednesday after showing symptoms that raised concerns ... but, thankfully, the baby's mom says the little girl's improving.

Keeta Vaccaro -- Tyreek's estranged wife -- shared the scary details of the incident on her Instagram page on Thursday ... writing her doctor advised her to get to a hospital ASAP on Wednesday night after baby Capri "started feeling warm, super sleepy, and just not herself."

"I called [ Dr. Jared Friedman ]," Keeta said, "and within minutes, he had us straight into the ER with an incredible team waiting for us."

Keeta said Capri went through a bunch of tests ... and, fortunately, it looks like her baby girl is going to be OK.

Vaccaro praised her doc for the ou

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