Archie Battersbee's mum said she has received a barrage of online abuse including death threats, and that a noose was left on her son's grave.
Hollie Dance, from Southend, fought to overturn a High Court ruling that gave doctors permission to switch the 12-year-old's life support machine off after she found him unconscious at their home in April.
Archie died on August 6 after the judge concluded with "profound regret” that his treatment was to end.
Ms Dance said the “very severe trolling” started in May, weeks before Archie's life support machine was withdrawn.
She described the trolling as “absolutely awful”.
“It’s been like it from mid-May,” she said. “The police have been investigating since mid-May so we’re hoping a case is building now.
“They are on it. We’ve got over 10,000 screenshots of some of the vile comments and accusations.”
Ms Dance said she was mostly targeted online, but there was also a “noose put on his grave” and “hanging ropes on the vigil tree”.
She added that she had received two death threats and the trolling had been "just constant, every single day”.
The mum also received complaints sent to Southend Borough Council after she celebrated Archie’s birthday with a gazebo at his graveside on Friday.
She said: "The fact they've now rung the council, the cemetery, they've said we've had this gazebo up and we're partying, we're playing music, eating, drinking, making it sound really quite bad."
"It sounds so bad and it's not the case. The gazebo, small gazebo was put up because rain was forecast on my birthday.
"It was bucketing it down at 3pm so we sat under a gazebo then the gazebo was taken down.
"It's like I'm not allowed to grieve, whatever I do."
The 12-year-old was rushed to hospital back in April after his mum found him unconscious with a ligature over his head.
Ms Dance believes Archie had been taking part in a viral online challenge.
Before his treatment ended, Archie was being kept alive by a combination of medical interventions, including ventilation and drug treatments.
But doctors said that continued life-support treatment was not in his best interests as they believed he was brain-stem dead.
Archie’s funeral was held at St Mary's Church in Prittlewell in Southend last month.
Martin Terry, cabinet member for public protection for Southend Borough Council said:
"We understand that people will always grieve in different ways when they lose a loved one.
"We would remind all families with loved ones in the cemetery of the conditions of when they purchased the plot, and to remind them that the cemetery is a public space that many people use to visit their loved ones, and as such we want to ensure that it remains respectful for all."
A spokesman for Essex Police said: "Our officers are investigating all the allegations and are working with the family."
