I have a lump on the left inside shin under my knee.ive had it for awhile but it never bothered me until recently.it seems to have gotten a little bigger....and when it gets cold it feels tighter?

Sounds like Baker's Cyst under the knee. They are usually benign, but when they grow bigger can become uncomfortable, even painful. Many times change in diet to include more Connective Tissue foods like bone broth can help. As can OTC analgesics or warm compresses. But it is best to see the PCP or Orthopedic Consult when they become bothersome.