Seemingly healthy son in law has blood clots both lungs

[Kurokage]

Sending lots of mojo!  I have a friend who was recently hospitalized with the same thing (hers had gotten so bad that she also had fluid around the heart.)  She's out now and in rehab, so I hope your SIL is quickly back to his old routines.

You're a good dad for fussing over them.  :)

Yeah, fluid around the heart can end up causing heart failure and future problems. but is sounds like this has been caught very early so the blood thinners should clear it up, the next step could be ultra sound.