Chargers star DL Corey Liuget claims his former trainer injected him with PEDs without his consent and cost him over $15 MILLION ... and now he's suing to get that cash back.
The NFL stud -- who's been with the Chargers since '11 -- was suspended for the first 4 games of this season after testing positive for a banned substance.
Now, Liuget's filed a lawsuit ... pointing the finger at his longtime trainer -- Ian Danney.
Liuget claims he went to get treatment for broken foot bones in November 2017 ... when Danney injected him with what he said was a "strong dose of an over-the-counter anti-inflammatory."
He says 2 days later he gave a urine sample ... and it came back dirty.
Liuget says he then confronted his trainer ... who admitted to giving him prescription medication -- but denied giving him a banned substance.
But, Liuget is still pissed ... and says it's cost him a fortune in salary and endorsements -- not to mention the public humiliation he says he's endured.
Liuget's asking for more than $15 MILLION in damages.
He's eligible to return to the field in 2 weeks.