The 23-year-old is understood to have suffered the bite in his Manchester apartment, but has revealed that he did not seek medical treatment until a week after the first symptoms - a small spot - started to show.
"It was a few Wednesdays ago I noticed what looked like a spot on my arm and I thought it was a bit weird. I trained on Thursday and Friday and played on the Saturday but I showed the spot to people at the club and had it wrapped up," Gray told The Sun.
"When I woke up on Sunday it was massive so I went to see the doctor when I went in on Monday and was told to keep an eye on it. I thought there was no way I couldn't train just because of a spot but on Tuesday I had markers put on it to see if it grew and by Tuesday night I was sweating badly and felt like I had a fever.
"I couldn't sleep and just felt horrible. My veins pop out at the best of times but they were really standing out and they looked red. The infection was going right up my arm."
Gray went on to describe what treatment had to be undertaken at the hospital, with surgeons ultimately forced to cut out the infection.
"On the Wednesday morning the doctor took the plaster off and the infection had got even worse and I was rushed to A&E," he added. "I got my bloods done and after a few more tests they were able to tell me it was a spider bite. I spent the next 48 hour in hospital on a drip, getting IV antibiotics into my body. They then sent me to theatre to have it cut out."
Gray, who spent time with Middlesbrough during his youth career, has since been released from hospital, but is not expected to return to training for his National League club until the middle of March.