i wouldn't worry about it bro... i get those lumps right under the skin you are talking about too... i have had 2 infections before... one in the chest and one in the shoulder... from my experiance when its infected its not a question.... i knew right away... sometimes i get knots from a bad shot... but when its infected its a huge fucking lump that feels mushy.... wait a week if by day 7 its the lump has not gone down in size and seems to be getting worse... go see the doc