A knot under my arm has been there for 2 wks. it continues to get worse & is now red, very sore, & bigger. what could it be & how do i get rid of it?

Axillary Boil: Usually a "knot" under the arm that is painful, red, warm and growing is a "boil" or glandular abscess. It must be examined and likely incised by a physician in order to allow it to heal. If it contains pus, it will not heal by itself and will likely get bigger. Sometimes it just bursts by itself (which causes relief) but the pain can be excruciating. Please see a physician who can examine you.

Infected gland/node: You have both the odor pproducing glands and lymph glands located in that area. The lymph glands tend to be round and movable and can be pushed around under the skin. Although sore, it seldom communicates with the skin directly, but seem deep to it. If infected, the odor glands tend to remain in a single spot and may have an inflamed surface connection.A warm compress can help, but see ur doc.