Hi Sara, how are you?
1) Are you menstruating? 2) How much soda do you drink?
These are the only two cases that ( I know of) that cause benign lumps in the breast area: Too much caffeine can cause a cystic breasts. While you are menstruating, the glands may become swollen, or enlarged. most Benign cysts are painful, however. From the location of the lump, I would say that you are menstruating and you just have a swollen gland.
If in 7 days it does not clear up,I would go and have some X-rays done to see if it is cancer. Some times women can get these lumps and they are not cancerous.
While waiting for results and time to get the X-rays, you can start our protocols. Most of them are rather inexpensive and can jump start your immune system.