A musomastix is an enemy of the muses. Therefore, anyone or anything that distracts you while you're trying to write is a musomastix.
Mastix was the Ancient Greek word for whip, and, back in the sixteenth and seventeenth century inventing -mastix words seems to have been a popular sport. A select few plucked from the OED are:
Popomastic - Inimical to the Pope
Histriomastix - An enemy of actors
Infantomastix - Somebody who agrees with St Augustine that unbaptised infants go to Hell
Female-mastix - Somebody who writes denunciations of women
The great thing is that you can just make a up a mastix word of your own. All you need is a prefix. So you could be a twittermastix, or workomastic, or practice gymmastix.
Confusingly, mastix can occasionally be the other way round. A theomastix is God's appointed punisher, somebody who wields God's whip for Him, rather than somebody who tries to whip God.
Anybody who does carry a whip, whether for reasons theological, equestrian or voluptuous, is, by the same root, mastigophorous.
I shall now leave you with hospitality-management advice from Hamlet:
...use every man after his desert, and who should 'scape whipping? Use them after your own honour and dignity: the less they deserve, the more merit is in your bounty.
Leave them be
And for a word utterly unrelated to whips, have a look at this old post of mine on backlash.