Veinous lump in penis

I'm 61 years od, and use Levitra.  About a month ago I noticed pain in my penis when erected..not serious, not there when the erection goes away..sex seems fine.  

Recently, I've noticed a vein like lump near the head of the penis..it is "hard"..more like dense..I can feel it and move it around..its maybe a centimeter in length and a millimeter or two in diameter..seems larger now than a month ago, and still hurts in erection.  The last two times I tried to have sex, the effect is that it seems the erection dies down , after entry..and, poof, its all over.  I've read the posts about Peyronies (sp?) Disease, worry about ability to have sex (which is a long standing..5 years using Levitra), worry about the "C" word.  Will this dissipate if I just lay low for a while? Is this common and I shouldn't lose any sleep, should I see my primary care doc ASAP?
Thanks