Lump under right armpit

Hey, I'm new here and I am absolutely terrified. 
 

For about a week I've been having little twinges of pain in my left breast. It literally twinges and then it goes away. I've been hearing / seeing a lot lately about breast cancer and so I've been obsessively checking my breasts due to my anxiety and OCD. I was checking them this evening and also checked under my armpits and found a bump under my right armpit. 
 

I'm going to contact the Dr's in the morning but I'm honestly petrified. I am 28. 

thank you