Sweet brother symptoms and conditions

I have 2 sons with asthma that have both been taken singulair (the oldest for 3 years & his brother for 2). My younger son's asthma got alot better since he was diagnosed & he was recently taken off Singulair thanks also to my husband hearing a report about the moodiness caused. When he was on it he would cry for no reason, get very irrational & seemed to think the world was against him. In just 2 weeks he is happy & cheerful and has told me he thinks it is due to being off singulair. His older brother's asthma has gotten worse over the years & I'm concerned about taking him off but he too has crazy moods. Just tonight he started a new soccer team & got crazy & suddenly didn't even want to participate in something he loves (wanted me to let him quit right then) until we argued enough he reluctantly participated. He then came home complained of a headache (which is also way too frequent) and now has been asleep for hours. Are there any alternatives to this drug? I'm a stressed out mom that doesn't deal well with these mood swings. He is normally a social butterfly & a sweet kid but lately seems more withdrawn, more irritable (especially tonight) & complaining about leg cramps in addition to these frequent headaches. I can't deal with too many more of these evenings & wonder if all these things are possible side effects. I'm glad to see my other son doing well but miss his normally sweet brother! Even his siblings think he is acting crazy :(