Any advice for a tired frought mum of a 17 month old?

My daughter has always beena fab sleeper (slept 7-7 from 9 weeks of age). About 6 weeks ago she started waking in the night, sometimes when we go to bed, sometimes at 2 or 3 or sometimes all of those times! She either cries for about an hour in shich time we go in, give her a quick cuddle and put her down. she stops crying as soon as you open the door. We have been doing controlled crying now every night (increasing to 10 mins beore we go in) and shes still waking. Last night she cried out every hour (but as if in her sleep) other times shes full blown awake! I dont think they are night terrors as she is comforted easily in my arms and is aware. I say its not teething as weve never had problems before and cant see any breaking through although she hasnt had her very back teeth through yet? Her room is between 21-24 degrees and she eats and drinks in the day and now has supper of porridge as well!? Funny thing is she sleeps at my inlaws twice a month and she sleeps from 7pm tim half 8 in the morning!!??? Aby advice or tips Im so tired!