Selena Gomez Countersues Perfume Co. -- You're The Real Stinker!!!

Selena Gomez believes a lawsuit filed against her by a fragrance co. belongs in the eau de toilette ... because the parfumeurs actually owe HER millions after their business deal fell apart -- TMZ has learned.

As we reported, the perfume company Adrenalina sued Gomez last month, accusing the singer of backing out of an endorsement deal worth millions of dollars ... and leaving Adrenalina up the creek without a spokesperson.

Now, Selena is firing back -- filing her own countersuit against the company, insisting she only backed out of the deal because Adrenalina was going broke ... and couldn't afford to manufacture and market her perfume line.

According to Selena's lawsuit -- filed by her attorney Michael Weinsten -- Adrenalina promised to pay her a 5% royalty on sales of all Selena-brand scents, including a guaranteed minimum of $5.2 million ... but it could barely afford to pay its own employees.

When she found out Adrenalina was going belly up, she claims she terminated the deal to protect her reputation.