Ok, sorry if I'm not much help as DS is only 11 months but to me it sounds like it could definately be teeth. DS was teething for about 3 months before his first teeth came through, so it can take a while.
Otherwise it could just be a phase. Probably not what you want to hear though sorry.
as for advice IDK, what about an amber teething necklace? I think as long as she's not having nurofen all day as well it should be ok to give it to her each night for a while. Maybe just give her a bit of extra water to help flush out her system if your worried? IDK if that'd help or not...

Sorry, I probably haven't been much help.