SMA is a genetic disorder affecting the control of muscle movement and leaves a child with no nerve signal which causes muscle fibres to waste away.
Born in Hawke's Bay, Tama has an electric-powered chair so he could move independently, but Geddes said even this was limited.
"That's really heart-breaking for me as a mum to see because I'd love for him to have that independence all day, every day but he can't."
Geddes said there had been many nights massaging Tama's legs so he would not wake up screaming in pain. And she worries about the regular X-rays on his hips because it is so easy for them to dislocate.
Geddes said she wasn't given much hope when Tama was first diagnosed.
"All we had been told was that this was a terminal illness, there was no cure and there was nothing that we could do," she said.
"All we could do was keep him comfortable and give him a good life. When that's your child, that's not enough.
Tama has a Givealittle page set up for him. In just a day, the page has received $450 in donations to go towards a large car that can transport Tama and his power-chair.
Geddes said it was frustrating to see the lack of money spent on preventing what is New Zealand's most deadly genetic disease.
She wanted to see more research into options like hydrotherapy so other parents would not have to see what she does.
"Having to watch him every day, fall over or not be able to hold himself up. Watching him lose the ability to do things that he was able to do and how fast it's happening," she said.
"When he's in pain, it's just hard because I can't take that pain away. I have to watch him go through it knowing that there's nothing that I can do for him."
Donations can be made at this Givealitte page