If Lexapro and celexa make you really sick (diarreah, nausea, insomnia and feeling like a zombie), will Paxil (paroxetine) also make you sick.

Celexa and Lexapro (escitalopram) are basically drug and pro-drug and would be expected to have similar side effects. There is no way to predict whether Paxil (paroxetine) would do the same but it is certainly possible.
Possibly. Paxil (paroxetine) is in the same class of drugs as Lexapro and celexa, with a similar side effect profile. Starting with a low dose may help minimize the side effects. Another strategy is to try a drug form a different class.