The former Beverly Hills, 90210 star sparked fears for her health in September (09) when she was admitted to a Los Angeles hospital with severe abdominal pains.
She was discharged hours later and her representative refused to comment on the diagnosis, stating Spelling had to undergo further tests at a later date.
She was forced to return to hospital again in November (09) after experiencing more stomach pains and she spent spent 10 days under doctors' care.
Tabloid reports speculated the hospitalisation was linked to an eating disorder after Spelling was snapped sporting a drastically skinnier figure, but the star continued to deny the claims.
Until now, Spelling has refused to comment on the health problem that caused her so much pain - but she's revealing all in her new memoir, Uncharted TerriTORI.
The star, 37, confesses she was struck down with a severe bout of swine flu, but was too embarrassed to admit it in public, especially after years of enduring cruel comments about her appearance.
She writes, "I was horrified. Swine flu was still a new phenomenon. News reports were describing a killer virus. If they got wind of my diagnosis the press would have a field day. Would they add this to the checklist? First I had a horse face, now I had the pig flu."
But Spelling insists she has overcome the virus and is working on piling on the pounds, reports People magazine.
She adds, "Now I'm on probiotics and vitamins... I weigh 101 (pounds) - my goal weight is 115. Finally I feel there's hope."