Have a small round lump under my right armpit and hurts regardless if I touch it or not? What is it? Will it heal on its own? Its been there 2 days

Many possibilities. While i recommend that you see a doc to be checked, sometimes the glands in our armpits can become irritated, inflamed and/or infected. Sometimes we use antibiotics, warm compresses and sometimes you need to have them lanced. For definite treatment however your doc needs to see what he is dealing with. Good luck.