But here's a curve of a recurrent nova, RS Oph:
Unfortunately there doesn't seem to be anything there that's an obvious sign of impending change.
Updated light curves for Betelguese.
AAVSO.ORG light curve generator
It looks to have started this group of mesurments back at previous levels, but them jumped back up to its almost brightest level again. While it doesn't look any more likely to blow up yet, it does appear that it may be developing some new variabilitiy.
Would these be the convulsions?
It's possible, but I think a few more years of light curves would be needed to make any sort of educated determination.