What Does A Itchy Rash Behind Shoulder Indicate?

Hi, Just want to ask... Had just returned overseas & that time sometime jan 17th I noticed a itchy little bite at the back of left shoulder in the hotel where i stayed but didn t mind it at all. when i came back overseas i noticed swelling on left supraclavicle (hallow above left collar bone) no pain but soft & swelling - no lump when i touched it...... sometimes it s hot & felt feverish... had a history of thyroid cancer 2012 -completely removed & radiotreatment... any comments/advice on this?