A hulking Queens gym teacher and former college football player claims a pupil fractured his ankle, injured his knee and forced him to go to a shrink for stress — even though the kid was only 50 pounds and in first grade.

Burly, 220-pound PS 330 teacher John Webster, 27, said a 4-foot-2 Rodrigo Carpio, 6, also kicked and pinched the Elmhurst school’s principal, a security officer and another teacher during a rampage in April.

“It’s sort of like an angel-devil sort of thing,” said the 5-foot-10 Webster, who recently filed a notice of his intent to sue the city and says he must now wear braces on his right ankle and knee.

“[Rodrigo] looks like an angel, but then, all of a sudden, that halo turns into horns. It’s been a nightmare. It’s embarrassing. It’s humiliating.”

But Rodrigo’s dad, Jorge Carpio, 44, scoffed: “The lawsuit is totally absurd. How could my little boy do so much damage? My poor son.”

The boy’s mom added, “This is a terrible thing to say [about] a child.”

“To every mother, their child is an angel,” said Josefa Marcia da Silva, 33, of her son, now 4-foot-3 and 64 pounds. “I know that he has problems, but he doesn’t deserve to be called such names.”

But Webster’s claims are backed up by an April 26 school “occurrence report” filed by the principal that says Rodrigo “was physically aggressive” and karate-kicked Webster in the knee and ankle that day.

Webster was accompanying Rodrigo and other students to the cafeteria for lunch when the boy started horseplaying, the teacher told The Post.

Webster said that he chided Rodrigo, but that the kid started kicking him.

“I tried to hold his wrists, and he began biting me,’’ Webster said. “I took him to the principal’s office, and he kicked me in the ankle, and one kick landed right on my knee. I felt a pop.’’

Rodrigo then kicked and pinched the acting principal and school safety officer, the occurrence report states.

NYPD responded but took no action. The boy’s parents refused to allow him to be taken to a hospital for observation.

Webster, who played tailback for upstate Morrisville State College, said his doctor told him he had to stay away from work for several months because of his physical and emotional state. But a Department of Education doctor told him to go back last month, so “I’m in limbo,’’ Webster said.

Meanwhile, Rodrigo is back at the school.

Webster’s lawyer, Andrew Siben of Bay Shore, LI, said school officials were repeatedly warned about Rodrigo but did not protect his client.

“This kid is clearly a tiny terror,” he said. “It’s sad that teachers like Mr. Webster are not offered protection from someone who can endanger other teachers and students.”

Rodrigo’s mom said her son is now on medication so he can focus.

“He is getting help, and he is much better now,” she said.

Both the school principal and the DOE declined to comment.

Additional reporting by Isabel Vincent