Hello its prob nothing but i have noticed swelling under left arm pit which is different to right side and nipple darker colour

and had a odd feeling in left breast For a while just feels heavy cant feel a specific lump just feels sore

should i be worried  ?

UPDATE 

• i left it for a few weeks and still didn’t feel right 

  got pain like bruises and a very very small indent and call not a lump but feels different to the other side 

  so saw gp and she has referred me to local breast clinic got appt next Monday 

  i feel like a fraud as feel prob just me and nothing wrong anyone else feel like this