For The Past Several Days I Have Been Getting This

For the past several days I have been getting this achy feeling across the middle of my back when I take a deep breath. It feels like I pulled muscles or bruised my ribcage but for the life of me I can't remember doing anything. It bothers me most when stretching the intercostal muscles. This afternoon, it is starting to be noticeable at the base of my rib cage in the front too. I am worried it may be the beginning of bronchitis or pneumonia and we have a friend's child who just had a tracheotomy. I don't want to go near him (or them) if I am possibly contagious and was exposed to bronchitis last week. Thoughts?