Sorry to say, but it sounds as if he's in a flare...I get painful muscle spasms in my shins also. I take zanafqlex muscles relaxer forth spasms, but those in the shins really hurt!
An exercise a neuro showed me for this: stand facing then wall legs spread. Keep legs straight as you lean on wall with hands. Turn feet inward (kind of oidgeon toed) and bend elbows...street he's those shin muscles. Massage also helps.
He does need to let his neuro know...even if he doesn't see him, he needs to know what his patient is experiencing. Good luck; let him know that MS can cause all sorts of weird symptoms...