hi frankshank, the blood rush might just be low blood pressure felt more now that your dropped 1.5 stone. i have very low resting blood pressure 95/55 and when i was younger i often had to crouch down if i jumped up to quick, so as not to faint. it was like a blood rush too and if my iron gets too low i sometimes get a pulse beat wooshing in the eardrum. you might also be a bit hypoglycemic (low blood glucose) from the fast and with your lowered body weight. this can have a similar effect to low blood pressure.
i had a gum ulcer once for many months which fortunately got resolved just days before the tooth was due to be pulled. as you probably know gum ulcers eat away at the socket bone and this widening space loosens the tooth and can move it out of alignment.
during my drama it was a great help visiting this forum http://members5.boardhost.com/CosmeticDental/
use the search option to pull up everything on gum ulcers, its gets discussed often.