I have been losing a lot of weight after finding out I was hypothyroid and going on levothyroxine. I recently found a hard lump on my collarbone down by my shoulder. I have had discomfort that moves for. My neck and into my arm for what may be are and I am still very tired. I don t know how long the lump has been there but I noticed it a week ago and it hasn t. Changed any. It moves but not by much and seemingly one direction only. It is uncomfortable messing we it. I am 29 years old. I do have an inhaler to see if it helps with my breathing thinking I may have exercise induced asthma. I feel like I will hit a wall and not have muscle tone or catch my breath and must stop a few minutes to rest and then I can restart.