We put my daugter on soy formula when she was about 8 months old and she's fine. She had a reaction to Yo Baby yogurt and to be safe we put her on soy instead of regular formula but she has no adverse reactions to cow's milk now. We're thinking it was a fluke, but better to be on the safe side.
If you have a Sam's Club membership you can get the Enfamil soy formula (I believe it's Isomil) at a really good price for a big tub. Also, if you ever travel on a plane you can get the individual packets of the Enfamil and Isomil to take with you.
Those were lifesavers when we went to South America.
We never had any problems with the soy and I still nursed while giving the soy so it was more of a suppliment. I will agree it smells and if you ever get some on your hands rinse them off, don't taste it, it's not worth the gag reflex, but the kids seem to do OK with the taste.
I hope the bug has subsided. My daughter's just over 20 months now and in the past two weeks she's only had 2-3 days of regular eating due to back to back nasty colds and she's dropping weight kinda fast. It's a tough thing to see but they do come out of the funk eventually to start eating well again. I feel your pain.
Good luck!!!!