It is tough when they are so young, the tests used for diagnosing can't be done because of their age. Older people could have a PFT done to test for asthma. Its not to say your babe doesn't have it just because they can't get tested. There are other things to watch out for. Educate yourself as much as possible and remeber to ask your doctor a very serious question. If you don't notice she has asthma, you need to find out what you should notice during an episode and when should you seek medical help. I know coughing, wheezing etc may accompany an episode. Also there are things that trigger asthma. Dust mite's fetal matter is one. You can freeze your kid's stuffed animals and get special bed liners to cut down on the exposure your babe has. Everyone's triggers are different though. It would also be beneficial to find out a list of triggers so you can help minimize their exposure to them.
Also remember that asthma is a disease that has episodes, while they might not experience symptoms 24/7, in a lot of cases it is important to take maintenance drugs to help prevent or limit the amount of occurances. They should also have a rescue drug like Xopenx or Albuterol for when things get really bad (a quick acting Beta 2 agonist). I appologize I don't know what class cromolyn comes under....... I know it is a mast cell stabilizer and helps to prevent allergic reactions that can cause asthma episodes. So, I assume its one of the maintenance drugs.