I recently found about a lump on my left side towards the bottom part of my rib cage. It's very hard, mobile, and painless. The whole side of my rib cage seems to be tender. A cyst has already been ruled out. Should I see a specialist?
Kait, when the doctor asked you to keep an eye on this lump, he wanted you to tell him if there were changes. Sometimes the way a lump changes is a big clue to what it is. Because the lump has gotten bigger and you are experiencing increasing rib tenderness, it's time to go back to the doctor. I'm not sure why you are sure that this could not be a sebaceous cyst. Both my husband and I have had them, but they don't always look exactly the same. The stress you are feeling could easily be contributing to your fatigue, so please go back to the doctor. Most likely the lump is not cancer because most lumps are not, but you need to find out for sure.
A common cause of pain such as you describe can be costochondritis, an inflammation of the cartilage that connect your ribs to your breastbone. It's typically treated with simple pain relievers (e.g., ibuprofen), and sometimes steroid injections. If your doctor hasn't considered this yet, bring it up with him or her.
Please know that the possibility of you having cancer is extremely low – especially since the lump is mobile, and breast cancer tumors typically are fixed in place. Breast lumps are usually caused by something other than cancer, such as fibrocystic change, a condition common in pre-menopausal women. While not dangerous, it can produce painful lumps. And it sounds like this lump is more in your side, rather than in your breast; so that would make cancer even less likely.
It sounds like you've already seen a doctor, since a cyst has been ruled out. But it would be good nonetheless to find out for sure what's causing this lump, and to get some relief from the pain, so you might want to get a referral for a second opinion from another doctor. Here are some links on pain management that you might find useful in the meantime:
Why Yoga Can Help Soothe Many Types of Chronic Pain
Using Mindfulness Meditation to Alleviate Physical Pain