I had the same issues w/ Lialda (nausea, anxiety, increased amount of BMs). I started taking it at night and was eventually able to sleep through the side effects. I've been using Lialda since November and then started also using Rowasa enemas in February. It's been a long road but FINALLY in the past 2-3 days I feel really close to remission(WAHOOOOOOOOOOOOOOOOOOOO).
Sorry to hear you had to go back to Pentasa - hope you feel better soon!