Too ill to work.. what else?

ok i was always told i had IBS ive spent 3 years wrking in a nursery with children and lost 2 jobs due to haveing diharea nd sickness and being off ill. after much a debate with the hospital i got tested for celiac disease and was diagnosed last september. i have alwasy been told by the doctor that my immune system is lower than a toddlers. ive since bin in a new job for 2 months and have bin ill and signed off by doc for last 3 an half weeks. caught an illness cough cold etc graduly got worse due to my dredfull immune system and they nw think itmay be glandular fever. have bin rushed into hospital twice this week. boss is now majorly hacked off that im having time off and im dreading that im going to loose another job again... what else can i do???// please help x