"The picture I'm posting is from this morning," Jessica wrote.
She continued: "and before you scream and cry 'why would she post a picture of him in a pull up, the indecency,' well 1. It doesnt show more than swimming jammers would and 2. Because life is not always politically correct and pretty, it is real.
"Life isn't pretty, and cancer destroys a person."
The photo was originally posted on Drake's own page, Stinky Joe's #1 Pit Crew - a title that combines Drake's love of cars with the nickname his mum gave him at birth - last Wednesday.
On Monday, just five days later, he was submitted to hospital due to severe dehydration and may be placed on a feeding tube, according to a post on crowdfunding site YouCaring.
This is just the latest struggle for Joe, who has been fighting cancer since he was diagnosed with leukemia September 2012.
Since then, he has undergone spinal taps to check for cancer cells in his spinal fluid, as well as blood transfusions and surgery.
But the most debilitating effects have been caused by the ongoing chemotherapy, which leaves him weak, tired, aching, unable to keep down food and water, and even affects his co-ordination and concentration.
Cruelly, he appeared to have gone into remission and was taken off chemotherapy in March last year, and was back to playing soccer in April.
But six months later he was diagnosed with testicular cancer, and forced to begin his fight over again.
Now Jessica wants to show just how brave her boy is.
She took the photograph of Drake in the bathroom only after she had carried him there, she says - his chemotherapy renders him too exhausted and weak. He must be carried or transported in a wheelchair everywhere.
The diaper he is wearing is necessary because he can't control his bowels or bladder '75 per cent of the time,' Jessica said, in her Facebook post.
He often falls asleep mid-conversation because he's so exhausted, she added, and frequently vomits up his medication - which can be as many as 44 pills in 24 hours - because he can't keep more than a spoonful of yogurt down.
"This is skin and bones, because I have to beg him to eat ONE green bean for supper, or drink a cup of water throughout the day," she wrote.
"This is having your son sleep with you at night because he is afraid of something happening and being alone, and by something I mean dying.
"This is having middle of the night conversations with a ten year old, asking if he dies will he go to heaven and will he see his dad there and be able to talk and play with him."
She continued: "This is him telling me, 'mommy, I'm not going to make it.'
"This is him not wanting to be touched, because it hurts too much, and using morphine to get through his day...
"This is him and me, telling him that I will continue to fight for him when he can't. This is him and me, and our world."
Drake's family are collecting money to help with his medical bills on YouCaring.
