I've had thrush umpteen times for over 20 years, including start of each pregnancy and several times during!
I use Canesten cream on "outside" areas and reduce/ keep off consumption of sugar & yeast (including things like wine, grapes, soft cheeses, mushrooms, jam, bread, honey, chocolate - list is endless!)
things to try to strengthen immune system : multivitamins, pro/prebiotic yogurt, raw garlic, manuka honey
My personal trick is to put the canesten cream on a tampon and up it goes, change 4 hourly, same during a period till it gets better.
I did check this with my gp and she said it was ok for me to do, but you should ask someone to see if it's ok for YOU!!!!!
I do this every time I go swimming as well, even if no symptoms to avoid picking another infection up in pool (use 1 before going, out when finished)
I very much doubt you can die from thrush! 
Get a vaginal smear to see what's going on, see gp.