It could be either bronchitis or pneumonia. First you need to have your chest listened to with a stethoscope. Secondly, you'll need a chest x-ray. Pneumonia is a radiological diagnosis in most cases. Judging from the fact that you have a young baby, I'm guessing that you're fairly young too. The chances of you having a bad pneumonia is not that high, BUT, you could still have a small one which is causing you all this grief. Additionally, the fact that you had a fever is also highly suggestive that you might have been infected with something. Get examined!