Vikki starts having "pains" after seeing Billy/Chelsea.
IMO, Vikki is her own cause of Vikki's stress, and as a rule I like Vikki.
BUT she is so obviously still in love with Billy, she wants him to beg and pine for her, while she strings Stitch along.
Alot of her stress would have just been relieved IF she would have just went on and had the paternity test, NOW. She can't pick who she wants as the father it is, what it is, she liked them both well enough at one time to have sex with them and get pregnant, and this is NOT Vikki's first go around with "who's the daddy", she did the same thing when she had sex with J.T and Brad to close together and they didn't know who Reed's father was either until after he was born, so she knows what causes this.