My son is 7 years old. He has been taking Singulair for about 4 ...

My son is 7 years old. He has been taking Singulair for about 4 months. His pediatrician switched him to Singulair after I complained that he was having severe mood swings, depression and anxiety. I suspected that the Pulmacort he was taking for asthma could be to blame. He still has some of these problems, but I think they have improved, however, he has suddenly developed a petichiea rash (I don't know if I spelled that correctly! It's a rash that looks like broken blood vessles all over his body). He looks AWFUL. I took him to 3 pediatricians and a dermatologist. The blood and urine tests they did on him all came back normal. The dermatologist found a picture and description in his book of this condition. It is called Chronic Pigmented Purpura, which basically means 'broken blood vessels'. He said the cause was unknown and it would "go into remission in 1 or 2 YEARS!" Anyway, I called my pharmacist and asked if this condition could be a possible side effect of Singulair. He said from the Singulair literature that a 'vascularitic rash (whatever that is) developed in 1.6% of Singular patients, which was .4% higher than the ones not taking it'. Has anyone out there been experiencing a rash like this??? I don't want to keep my son on a drug that would do this to him, but his asthma is much better since he started the Singulair. I don't know what to do.