A 15-year-old is suffering from a severe infection after a senior student forcibly injected a chemical into his penis at their school in Nakhon Si Thammarat.

The boy, nicknamed Aye, and his mother, Jutamad, visited a hospital in Nonthaburi for treatment on Tuesday. They were accompanied by internet whistleblower Guntouch Pongpaiboonwet.

A Mathayom 4 (Grade 10) student in Nakhon Si Thammarat, the boy said that on Aug 1 he had been forced into a toilet cubicle by a senior student who then used a syringe to inject the substance into his penis.

Aye said that in subsequent days his penis became swollen and painful with the infection making it difficult for him to urinate.

The boy, who admitted being bullied at school, said he did not know his attacker and insisted the injection was done against his will.

Ms Jutamad said she took her son to a local hospital in Nakhon Si Thammarat but was turned away because there was no specialist there. The boy was referred to another hospital for treatment after his condition did not improve.

Ms Jutamad said she then filed a complaint with police, but weeks later, they appear to have made little headway.

In the meantime, someone from the school visited the boy at home and offered a gift basket along with 1,000 baht in cash as compensation.

According to Mr Guntouch, the senior student recorded himself committing the crime and shared the clip with friends at school, causing the boy humiliation.

A doctor at the Nonthaburi hospital said some nerve tissue around the penis had been permanently damaged and complex treatment was necessary to treat the boy.