"I'll be having surgery soon," the 26-year-old Bellator fighter says, adding ... "I'm just having some numbness in my fingers right now, and they're just waiting for the numbness to go away, and then immediate surgery. They say I'll probably be out 4 to 6 months, so it's not that long."

Of course, Pico, the number 4 ranked Bellator featherweight, dislocated his shoulder throwing a hook within 30 seconds of the first round of his fight with Jeremy Kennedy. Miraculously, Aaron was able to survive nearly an entire round with his shoulder dangling.

In-between rounds, Aaron directed his coach -- who obviously isn't a doctor -- to pop his shoulder back into place. Unfortunately, they didn't have any luck. That's when the ringside physician came to the cage and ultimately stopped the fight, despite Pico pleading with him to fix the injury and let him continue.

Aaron addressed fans who've attacked his coach for trying to get the shoulder back in the socket. He also tells us why the ringside doc wouldn't just pop the shoulder back in place.

Officially, Aaron lost the fight ... but the fact he was able to scrap 4+ minutes with a serious injury is insane, and goes to show how tough he is.

Shockingly, Pico says the injury didn't hurt ... at first.

"I just felt stuck, like something was blocking it, but I wasn't in pain," Pico says, adding he immediately left the cage before Kennedy was announced as the winner because he recognized he needed to get to the hospital.

Then the adrenaline wore off ... and well, it hurt, bad.

"Then when I got to the back, the pain really set in, and then when I got into the ambulance, I can handle pain, but I started to shed a few tears because I was like this thing is the worst pain I've ever been in."

It was just last week that Pico, along with best friend and fellow Bellator star AJ McKee, came to the TMZ office and sat down with Babcock on the "TMZ Sports" TV show (airs weekdays on FS1) ... and vowed to be champion one day soon.

Aaron's injury may have delayed his goal ... but it did anything but derail it.

In fact, he's already thinking about his return ... and ideally, he'd fight the guy at the very top of the division, Patricio Pitbull.

"If I'm being selfish, of course, I'd like to go straight for the title, but I believe Jeremy Kennedy deserves a rematch."

"If I need to fight him again, I will. If they want me to fight for the title, it's all good. I have nothing but respect for Kennedy. He didn't know my shoulder was out and he came to fight. Tough guy, s**t happens. There's nothing you can really do.".