What Does Shadow Between Ribs In X-ray Indicate?

i have had an xray and my doc wants to see me next week, a shadow between my 7th and 8th rib has shown up, and mentioned i wont be going for another xray until 4-6weeks....should i be worried, ive been crying all day i am so scared as we are going through lung cancer with my dad at the moment. thank you for your time