What Causes Intermittent Painless Swelling Between Neck And Collar Bone?

I have intermittent painless spongy swelling between left side of neck and collar bone, this has been occurring for 4 weeks. I also have swelling over my thyroid in my neck on right hand side. I have had blood test on thyroid which was normal. Last couple of days I have had intermittent stomach pain, not like a stomach bug pain but more a deep sharp pain.
Could you give me a idea of what is wrong, thank you.