My 12 year old son started on Singulair 10 days ago. Yesterday, h...

My 12 year old son started on Singulair 10 days ago. Yesterday, he threw up blood twice, so I took him to urgent care. He said it felt like someone was shoving knives into his stomach. He had blood tests and a CAT scan -- the connective tissue in his abdomen was inflamed and his lymph nodes are slightly enlarged. His white blood cell count is up slightly -- just above normal -- and his liver enzymes are elevated, which the doctor said is common with a viral infection. He has also had migraine-type headaches twice in the last week. HOWEVER: my 16 year old son has been on Singulair for four years, and it has been a lifesaver. He has had some hand tremors, which could also be aggravated by the decongestant he also takes, but no other side effects.