I just started birth control 3 days ago, is it normal I have a stinging pain in my underarm? There's no lumps because I just got check out.

It could possibly be related because birth control (I'm assuming pills) do affect your vascular system, and areas of the body such as the breasts, and the underarm nerves are related to the breasts... but this is only speculation, and you need to tell the prescribing doctor or clinic. Do you smoke??

I do not smoke, and thank you it makes a lot of sense. Do you think I'm allergic to the birth control?