Singulair and feeling overwhelmed

I rarely post, but my terrible experience with this drug, requires it. I've taken dozens of different drugs over the years, and almost never suffer side-effects. I took a dose of Singulair about 10pm, awoke at 4am with severe light-headedness, dizzy, feeling overwhelmed, nausea, incredible weakness, loss of balance, and generally, feeling absolutely dreadful. By 6am, I found myself vomiting. By 8am, I made the trip to the ER. My heart rate and BP were all over the place. As there wasn't really anything they could do, I was sent home. Slowly, I started to feel better as the Singulair (thankfully) left my body. The next day, things were pretty much back to normal. Please use great caution with this drug - I (obviously) will stay far away from it!