My first "real" ecigs were Blus and those gave me sore throats all the time, even with a decent amount of water consumption. (Warning: Unscientific opinions to follow) My understanding is that Blus are 100% VG (or thereabouts), with 24% nic (yours is much less), so my guesstimate is that maybe you have an issue with VG? I've been puffing PG/VG mix since then, at 12%, and haven't had any more sore throats. So many variables with ejuice, it's hard to say - hope you are able to find something that works!