It certainly is, and shows that you are run-down. You need to build yourself up a bit. Take vitamins, minerals and probiotics. Cut sugar and alcohol out for a while, too.
yeah, cystitis is infection of the bladder, thrush is a fungal infection, which usually presents in the genital tract
make sure you consult either a GP or go to a genito-urinary medicine (GUM) clinic, as this suggests you may have other problems too