If you had bloody poop, you may have been defeated before the chicks ever arrived. Is your brooder well enclosed or is it made of wire around the sides? I am not getting why the heat lamp wasn't sufficient all by itself? If you had the thermometer in the general area of the lamp, it should have been enough to get the temp up if it (the heat lamp) was lowered enough into your brooder.
The entire brooder doesn't have to be 100 or 99 degrees, just enough area that all the chicks can All get near that 99 degree mark. When I have chicks in my brooder, they wander in and out of the heat range. I try not to 'cook' their food and water at that temp, so the chicks range out to eat and drink, then bring home what they've found and digest under the light. But I will say, all four sides of my brooder are solid for the new hatches.