Long Tern Side Effect Of Soreness?

Hi. Gary, hubby, was finished with chemo Feb of this year. Lately he has been experiencing major soreness...not pain. It travels. It was on the front of his thighs but today it is in the upper arms on both sides. He has had scans but it doesn't seem that the cancer has spread. Could all this muscle soreness be caused by the chemo?

He has nsc lung cancer stage 3B. Thank you so much.