I vaguely recall something about occasionally getting a mana parasite in the swamps around Riverhaven. Is that a thing or am I looking at something else? I was hunting swamp trolls for a while and I noticed my mana bar was pulsing down instead of up and now it's stuck at 7% and bounces down to 3% and back to 7 every pulse. Been going on for about 15 minutes maybe...

Just double check you aren't using a cyclic too and forgot about it.