Sounds more like pleurisy or a form of costochondritis. The former can be viral. The latter is also inflammatory but musculoskeletal. Both can come and go and take weeks to resolve.

What can elevate the d-dimer? HRT, pregnancy, any resolution of any clotting (including external bruises, small amounts of internal bleeding, hemorrhoids, etc)... the d-dimer test is great if it is NEGATIVE. It is incredibly nonspecific and not helpful if positive because so many things can elevate it. The ONLY role of the d-dimer test (and there are several varieties; only two are reliable, and many hospitals still use the older kinds) is to test a low-risk patient and move them into a very low risk post-test probability pool. (Say that three times fast!)