Nic-sorry to hear that you're feeling ill again. I know DS cycled feeling really awful every 3 weeks and would have to stay home the entire week and I believe it had to do with the life cycle of Lyme which in men is 3 weeks/women with their monthly cycle from what I've read here. I'm not sure of the life cycle of Bart but if you have Lyme as well, it could be Lyme acting up.
Parent of teen DS w/ CDC+ Lyme test Nov 2015, late stage Lyme + mycoplasma (stubborn/lingering), bartonella, babesia. Currently treating with pulsed antibiotics, moving toward maintenance and headed into remission - no sick days this school year yet
Website I started: ParentsofLymeKids.com
aka Lyme Disease 101 for Parents