My EBF 5-month old has gone on a nursing strike. 

This started last night. She's been waking every 1-2 hours during the night over the past few weeks and would always be nursed back to sleep, but last night she just refused. She arched her back and screamed when I tried to feed her in the cradle position, which made me think it was painful reflux (she takes ranitidine for this). But then she also clutched her ears and poked her gums, which made me think it was ear ache and/or teething.
The only thing that's worked has been giving her a dose of calpol. She's fed twice since the strike starting, straight after calpol each time. But surely this isn't sustainable.
I feel so sad and really desperate. I didn't think babies went on nursing strikes this early. I also just don't know what to do about it. I'm worried she's not getting enough food/hydration and that I'll lose my supply. Any advice please?