You should really get your own test kit. More often than not, the lfs
doesn't do it correctly or can give you faulty readings. In cases of emergencies like this, it's great to be able to have your readings done in a few minutes time.
It sounds like you're going into a mini-cycle. If you removed the filter entirely, and started over with a brand new one, you've lost your cycle.
75: blood parrots, featherfin cat, emperor tetras, turquoise rainbowfish, BN plecos, japanese trapdoor; 46: WCMM, gold inca snails, ghost, bamboo & amano shrimp, kuhli loaches, rummynose & ember tetras, endlers, platies, flame gourami, guppies; 16: pygmy, peppered, loxozonus corys, otos, assassins, RCS ... ~ Research PRIOR to purchase.... ~