Christina Burns, Antwain's mother, tells TMZ ... his GoFundMe was created in March during one of his many stays in the hospital and it's now raised $72,000, with $22k being donated since he passed away on Sunday. She wants to put the money towards keeping his legacy alive, in the form of a restaurant called, "Where We Bout To Eat At."

Antwain's mom says the $22k raised in the past few days will be put towards kickstarting the business, with the other $50k helping pay off Antwain's hospital bills and other family expenses. Christina says she will help create the menu, but needs help managing the other aspects of a restaurant. The menu will be versatile with seafood, chicken and other grub -- so you won't have to look much further when you're asked "where we bout to eat at?"

The viral sensation had a ton of catchphrases, which will be reflected on the menu ... for example, Antwain's mom is already planning some "You Have Cheese Like Me" mozzarella sticks.

After Antwain went viral, his mom says she tried starting a seafood truck biz ... but after mapping things out, she just didn't have the time to commit to getting the biz up and running because she was busy taking care of him and her other 3 children.

As we reported ... Antwain died Nov. 21 after fighting a rare autoimmune deficiency his mother says caused him to be consistently in and out of the hospital ever since he was 4 months old. He was only 6.

His mom is shedding more light on his death ... she says Antwain was home when she heard his ventilator sounding off an alarm. Typically, Antwain alerts his family when he's experiencing pain or has trouble breathing, but this time he was silent.

Antwain's mom says police and an ambulance responded to their home and attempted to resuscitate him, but had no luck ... he was taken to a hospital where doctors fought to keep him alive, but were ultimately unable to.