Illness - Fear of Losing job

I hold a management position for a large company. I have several illnesses that bring on fatigue & depression and for which I am being treated. I have lost work due to this and have only been with the company 7 months. I was laid off for 14 months previous due to the economy. I have worked in my field for 24 years and have always had great reviews, however when my health started to decline, so did my work.

I recently was diagnosed with a herniated disc and am getting cortisone shots which are not working, am in severe pain and cannot take painkillers at work obviously due to drowsiness, so I am suffering with severe pain at work in my back and leg that affects my concentration. I have begun walking with a limp and again have 2 other illnesses that exacerbate this pain. Multiple Sclerosis and Diabetes. I feel "off my game" and don't know how to get back on it. I feel so very fatigued at work and do not feel that I'm a team player right now, which I want to be again, but the physical pain is excruciating. Walking, sitting, driving.

I want so much to be back to "normal", but this recent diagnosis has only exacerbated my other illnesses. My Boss is aware of this and has been very understanding. I have Doctor's notes and just am so afraid of losing my job due to this time out. When I'm on my game - I'm great. But the fatigue, pain and depression that these illnesses are causing me is just too much.

I want nothing more than to be on my game again but the physical pain distracts my concentration. I supervise people and cannot show them what I'm really feeling. Can I be fired for having these illnesses, doctors notes and losing time? I really love my company and job and they are very understanding and a great company, but I understand they have a business to run and without me playing my part as a team player because I am home sick and in pain, I don't know what to do.

I'm sorry this is not a success story per se, but I would appreciate some advise. I have been honest with both my Manager, Director and Human Resources. I'm afraid. Especially having been out of work when the economy slumped in 2008 and living in one of the highest rate of unemployment states.

Thank You for your consideration.