Hi there!
If the swelling is present on just one side of the chest, it is likely to be due to infections/ inflammations or growth from any of the superficial or deep structures. Without an evaluation and probably a few tests, it would be difficult to determine the cause of the chest wall swelling. It would be best to get this evaluated by a primary care physician for an accurate diagnosis and appropriate management,
Hope this helps.
Take care!
Do you have any chest pain? Why are you taking l-carnitine? Is your weight-training under medical supervision?
I would definitely not continue the weight-training until I saw a doctor. Continuing the l-carnitine depends on whether a doctor prescribed it and how long you've been taking it. If the l-carnitine and weight-training are brand-new at the same time and a radical change to your body's normal state of being, something's been shocked or traumatized (this is not necessarily bad--when you build new muscle you have pain because your muscles have been traumatized). You need in-person evaluation. Even if the swelling goes down, you need to know the cause to prevent it from happening again. Consider going to an urgent/community care center tonight or tomorrow. If you have chest pain, call an ambulance immediately. Otherwise, call your regular doctor on Monday.
If the l-carnitine is self-prescribed, please remember to be careful when you take any medication or supplement. You really should have your doctor's approval to ensure that whatever you put into your body won't harm you (which is more important than the idea that something can help you).