Fired for Insomnia - is that legal?

[Rebecca L]

I worked at a day camp since June 16, 2008. Just this Wednesday (July 30, 2008), I was let go. The reason my boss gave was that I wasn't getting enough sleep and therefore I couldn't perform well. This is true - I wasn't performing well. However, in March 2008, I was diagnosed with insomnia. Last week (Monday July 21 - Friday July 25) was a particularly tough week, as was Monday July 29. I was fighting to keep my eyes open, and I had no energy. That night (the 29th), I found that I had a 99.5 temperature. The next morning, I still felt sick to my stomach, and called in saying I didn't think I could come to work. Over the phone, my boss told me not to come in, but threw questions about my condition at me in a semi-attacking sort of way. Later, he left a message on my cell telling me we had to talk and that "this was unacceptable." I had a 99.8 fever and was throwing up.

When I went in to meet with him early Wednesday morning, I felt better, and didn't have a fever. I had surprisingly gotten a fair amount of sleep the night before. When I sat down, he started by telling me that he hired me because I was exactly what he was looking for, and then proceeded to talk about how my performance was not good enough. This was also after he gave me an "outstanding evaluation" (his words) on July 18, with only a 6/10 for stamina due to two days I went home sick in the first two weeks, one for lack of sleep and another for slight dehydration. He brought up my calling in sick on Tuesday, but when I told him I was legitimately sick and had a fever, he retorted, "When you get little sleep, your body gets sick. For these reasons I will have to let you go."

I found out later, through a phone conversation my dad insisted he have with my boss, that I was apparently on probation for those two days I went home in June, regardless of that outstanding evaluation he gave me in July. I had no idea.

Is what my boss did legal?