Cluster feeding at 5 months

My lo is exclusively breastfed and has, over the last month or so, fallen into a pattern of waking twice in the night to feed. Suddenly tonight she has woken every 45-90 minutes since I first put her down at 8. Nothing soothes her, I've given her calpol as I thought it might be a teething issue, I've tried cuddles and rocking her back to sleep...only boob will do.