Sorry to hear of the troubles you're having but happy to see you here! Spasticity is defined as an abnormal increase in tone or stiffness, so it could potentially be due to spasticity, and it would be a good idea to keep your GP and/or neurologist informed. Source: https://www.ninds.nih.gov/Disorders/All-Disorders/Spasticity-Information-Page Could it be possibly due to unrecognized straining of it during the daytime? I ask because when things are new, there can be a tendency to attribute everything to MS, and MSers of course still get all of the same stuff that others do. I only mention it because sometimes doctors can shrug things off as always being related to the MS, and sometimes that can be a barrier to good care (because sometimes stuff isn't related). It can be a bit difficult to tell these things apart, but yes, it could be, it also might not be (how long it sticks around for might help a little in figuring it out). Also, sometimes if we have lost a little sensation from the MS, we might not be aware that we've been straining something unless well after. Apologies, I had to fix typing errors in my comment (for some reason we can't edit posts)