Raheem Bailey, 11, caught his ring finger on a fence as he tried to flee a group of pupils at Abertillery Learning Community on Tuesday, his mother said.
Police are now investigating a report of an assault on Raheem at the secondary school, and the school trust closed all of its campuses on Monday.
His mother Shantal alleges Raheem was beaten then kicked on the the ground by a group of children and broke his finger while climbing a fence to escape his tormentors. It later had to be amputated after a six-hour operation failed.
Speaking to the PA news agency on Sunday, Ms Bailey said: “It is difficult, as a mum, having to tell your child that people might not like you because of your skin – not because you’re mean, not because you’re horrible, but just because of the skin he was born into.”
“The whole time (he was) telling me ‘I’m sorry, I’m sorry mummy. I just couldn’t, I couldn’t stay there, like why does no-one like me?’ Ms Bailey said
“These are things that my child, while being in pain, is constantly having to ask me, ‘mummy, why does no-one like me? Like why? Why did they pick on me?’”
Nearly £100,000 has been raised on Go Fund Me, in just three days.
His mother said of the incident: “Raheem has faced racial and physical abuse, as well as more generic bullying about his height and other things, since he started secondary school.
“On Tuesday, Raheem was attacked by a group of children and beaten (mainly kicked) after being pushed to the ground.
“Consequently, Raheem made a desperate attempt to leave the school grounds in order to escape the situation.
“Whilst climbing the fence, his finger got caught and attached to it, causing the skin to strip and the finger to break in half it. After 6 hours of surgery to save it, which was ultimately unsuccessful, his finger had to be amputated.”
Gwent Police have confirmed it is “currently investigating a report of an assault of an 11-year-old boy at a school in Abertillery on Tuesday 17 May”.
In statement issued late on Sunday on Twitter, Superintendent Vicki Townsend said: “Our officers are supporting and liaising closely with the family of the young boy who, when leaving the school grounds following the reported assault, received a serious injury to his hand as a result of it being caught in a fence.
“Since we received this report, on Wednesday 18 May, there has been significant interest and coverage of this. I would urge people to think about the impact their social media posts and commentary could have on those affected, as the police investigation continues. We’re working closely with the school and officers continue to carry out enquiries in the area.”
In a statement, also issued on Sunday, Blaenau Gwent County Borough Council said that all campuses at Abertillery Learning Community would be closed on Monday. The statement read: “Abertillery Learning Community is working with Gwent Police in relation to an ongoing investigation into an alleged assault on the secondary campus.
“All campuses at Abertillery Learning Community will be closed tomorrow on health and safety grounds. Learners will access blended learning for Monday, 23rd May. The safety and well-being of learners and staff remains of paramount importance to the Learning Community and the Local Authority at all times.”
Boxer Anthony Joshua and footballer Jadon Sancho are among those who have sent messages of support to Raheem since the incident.
US basketball player Gerald Green, who forged a hugely successful career with nine fingers, has even set up a call to speak to Raheem directly.