Farmer's Lung

I've been spreading mulch on my garden. The mulch is old and full of mold. When I stir it, a fine white dust rises and I breath it. The first time I spread mulch I don't remember what happened. The second time I got a terrible cough and felt a bit feverish for a few hours, but was totally recovered within 40 hours. The last time I spread mulch was yesterday. I tried to avoid breathing the dust and worked with the mulch for only a short time. Then I had trouble sleeping and I got an ear ache and I lost about 30% of my appetite.

The causality is pretty obvious, and the symptoms are a near-perfect match. I have Farmer's Lung:

Farmer’s Lung is a noninfectious allergic disease. Basically, an individual becomes allergic to dust and mold. With Farmer’s Lung, the immune system cannot adjust to the mold spores. Farmer’s Lung has these symptoms:
• Fatigue
• Chills [almost]
• Shortness of breath
• Tightness in the chest
• Headache [not so much]
• Irritating cough
• Loss of appetite

Respiratory symptoms vary with the amount and intensity of exposure. After a first reaction, a worker is likely to develop an increased sensitivity. Then, a worker can have a more severe reaction with fewer exposures.

... Organic Toxic Dust Syndrome has similar symptoms but does not involve the immune system. Organic Toxic Dust Syndrome goes away after it runs its course. It often hits all the workers in a group at one time.

Source: http://ohioline.osu.edu/aex-fact/192/pdf/0192_1_11.pdf

Update: I spread mulch a few more times with no symptoms. False alarm? Maybe. Or the dust composition of the mulch pile has changed due to decomposition.