Everyone's different. I got more anxiety when they upped me to 30mg, and also got increased pressure in my head and insomnia. But it never did work all that well for me. I think when a medication works well everything is different than when it doesn't, including side effects.
there's a lot of things that could happen...most of them aren't anything to really be worried about. it's really a question for your doctor. how long have you been on the new dosage? i'm sure you'll need to give it a few weeks to know whether it's effective or not. try not to worry too terribly much if your symptoms are returning. this will only make things worse. one reason not to let yourself worry is because it isn't uncommon for symtpoms to return occasionally even when taking meds....but just because they return sometimes doesn't mean the meds no longer work. you may just be having a bad time and it will pass eventually.