V.B.
I'm so sorry to hear about your baby! I just wanted to give you another perspective or question to ask about this. My son was diagnosed with something called ITP when he was 13 months old. I took him to the pedi because he had a weird rash (which turned out to be petechia also). They sent us to the Children's Hospital ER immediately. His platelet count was 5,000 (you may know that it should be 150,000-400,000). I'm not sure what is leading your son's doctors to believe he has this other disease, but ITP can be caused by a virus (thus, the fever). The body (spleen) just starts mistaking the platelets for the virus and pulls them out of the bloodstream. It corrects itself over time, although my son was given steroids to boost his platelet counts. There are other treatments as well, but the side effects were not something we wanted to deal with, so we gave it some time and within a couple of months, our son was completely back to normal. He is 2 now and hasn't had any other issues with it. My son was never sick before he got this (which is what usually happens), so they concluded that he got it from his MMR vaccine at his 1 year appointment. It is a live virus vaccine and it is SO rare for that to happen, but it did in our case.
I guess what I'm trying to give you is hope. Hope that maybe your son doesn't have this disease they are suspecting. Maybe you can mention ITP to his doctors and see if that is a possibility. I'm not saying that they don't know what they are doing, but those are the exact symptoms my son had, so it's possible! ITP is curable and generally doesn't recur. I'm so sorry that you're scared. I was terrified too since they told us that any injury or fall could result in internal bleeding. Of course, being 13 months old, my son fell, walking in the kitchen, the morning after his diagnosis and hit his head, so we had to go back to the ER to get a CT scan and make sure he wasn't bleeding into his brain. Thankfully, he was fine, but he looked like someone beat him up for over a month. The bruising didn't heal very quickly because of his low platelet counts.
I will say a prayer for you and your family. I know how scary this can be since we went through a similar situation (Lukemia was discussed in our situation too). I hope that you get some answers sooner rather than later and that your baby stays as healthy as possible in the meantime.