My Husband Just Completed 8 Months Of Chemo For Non

my husband just completed 8 months of chemo for non hogkins lymphomia and today we were advised he has a blood clot in his lungs. Is this a normal outcome of chemo? What could have caused this to happen? He had a lung function test done approx. a mo ago and while it was not a perfect outcome it was not something to worry about according to the Dr.